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a(n) is the smallest nonnegative number whose American English name has the letter "e" in the n-th position.
+10
13
8, 0, 1, 3, 3, 12, 13, 17, 21, 23, 23, 73, 101, 103, 103, 112, 113, 117, 121, 123, 123, 173, 323, 373, 1103, 1103, 1112, 1113, 1117, 1121, 1123, 1123, 1173, 1323, 1373, 3323, 3373, 11373, 13323, 13373, 17373, 23323, 23373, 73373, 101373, 103323, 103373, 111373
OFFSET
1,1
REFERENCES
GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 70.
EXAMPLE
a(1)=8 ("Eight"), a(2)=0 ("zEro"), a(3)=1 ("onE"), a(4)=3 ("thrEe").
PROG
(Python)
from num2words import num2words
from itertools import count, islice
def n2w(n):
return "".join(c for c in num2words(n).replace(" and ", "") if c.isalpha())
def A164790(n, t="e", i0=0): # t is target letter, i0 is start
return next(i for i in count(i0) if len(w:=n2w(i))>=n and w[n-1]==t)
print([A164790(n) for n in range(1, 38)]) # Michael S. Branicky, Apr 21 2023
(Python) # faster for initial segment of sequence; uses n2w/imports above
def A164790gen(t="e", i0=0, offset=1): # generator of terms w
adict, n = dict(), offset
for i in count(i0):
w = n2w(i)
if t in w:
locs = [i+1 for i, c in enumerate(w) if w[i] == t]
for v in locs:
if v not in adict: adict[v] = i
while n in adict: yield adict[n]; n += 1
print(list(islice(A164790gen(), 50))) # Michael S. Branicky, Apr 21 2023
CROSSREFS
See A362120-A362122 for other versions.
Cf. A164789 ("o"), A164791 ("n"), A164792 ("t"), A164793 ("i"), A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").
KEYWORD
nonn,word
AUTHOR
Claudio Meller, Aug 26 2009
EXTENSIONS
a(25) and beyond from Michael S. Branicky, Mar 25 2021
Name edited by N. J. A. Sloane, Apr 20 2023
STATUS
approved
a(n) is the smallest nonnegative number whose American English name has the letter "n" in the n-th position.
+10
9
9, 1, 9, 20, 7, 11, 15, 13, 17, 47, 27, 77, 109, 120, 107, 111, 115, 113, 117, 147, 127, 177, 327, 377, 1120, 1107, 1111, 1115, 1113, 1117, 1147, 1127, 1177, 1327, 1377, 3327, 3377, 11377, 13327, 13377, 17377, 23327, 23377, 73377, 101377, 103327, 103377
OFFSET
1,1
REFERENCES
GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 70.
EXAMPLE
a(1)=9 ("Nine"), a(2)=1 ("oNe"), a(3)=9 ("niNe"), a(4)=20 ("tweNty").
PROG
(Python)
from num2words import num2words
from itertools import count, islice
def n2w(n):
return "".join(c for c in num2words(n).replace(" and", "") if c.isalpha())
def a(n):
return next(i for i in count(0) if len(w:=n2w(i))>=n and w[n-1]=="n")
print([a(n) for n in range(1, 41)]) # Michael S. Branicky, Apr 21 2023
(Python) # faster for initial segment of sequence; uses n2w, imports above
def agen(): # generator of terms
adict, n = dict(), 1
for i in count(0):
w = n2w(i)
if "n" in w:
locs = [i+1 for i, c in enumerate(w) if w[i] == "n"]
for v in locs:
if v not in adict: adict[v] = i
while n in adict: yield adict[n]; n += 1
print(list(islice(agen(), 50))) # Michael S. Branicky, Apr 21 2023
CROSSREFS
Cf. A164789 ("o"), A164790 ("e"), A164792 ("t"), A164793 ("i"), A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").
KEYWORD
nonn,word
AUTHOR
Claudio Meller, Aug 26 2009
EXTENSIONS
a(25) and beyond from Michael S. Branicky, Mar 25 2021
Definition clarified by N. J. A. Sloane, Apr 20 2023. We also need a British English analog of this, just as A362121 is an analog of A164790 (a(13) will be different).
STATUS
approved
a(n) is the smallest number which has in its English name the letter "o" in the n-th position, or -1 if no such number exists.
+10
8
1, 4, 2, 0, 4000000000000000000000000000, 41, 21, 24, 22, 72, 101, 104, 102, 304, 302, 141, 121, 124, 122, 172, 322, 372, 1104, 1102, 1304, 1302, 1141, 1121, 1124, 1122, 1172, 1322, 1372, 3322, 3372, 11372, 13322, 13372, 17372, 23322, 23372, 73372, 101372, 103322, 103372
OFFSET
1,2
EXAMPLE
a(1)=1 ("One"), a(2)=4 ("fOur"), a(3)=2 ("twO"), a(4)=0 ("zerO"), a(5)=4*10^27 ("fourOctillion").
CROSSREFS
Cf. A164790 ("e"), A164791 ("n"), A164792 ("t"), A164793 ("i").
Cf. A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").
KEYWORD
word,sign
AUTHOR
Claudio Meller, Aug 26 2009
EXTENSIONS
a(5) corrected and a(23) and beyond from Michael S. Branicky, Mar 25 2021
STATUS
approved
a(n) is the smallest number whose English name has the letter "t" in the n-th position, or -1 if no such number exists.
+10
8
2, -1, -1, 15, 8, 17, 22, 72, 13000, 48, 28, 78, 302, 115, 108, 117, 122, 172, 322, 148, 128, 178, 328, 378, 1115, 1108, 1117, 1122, 1172, 1322, 1148, 1128, 1178, 1328, 1378, 3328, 3378, 11378, 13328, 13378, 17378, 23328, 23378, 73378, 101378, 103328, 103378
OFFSET
1,1
EXAMPLE
a(1)=2 ("Two"), a(4)=15 ("fifTeen"), a(9)=13000 ("thirteenThousand"), a(13)=302 ("threehundredTwo").
CROSSREFS
Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164793 ("i").
Cf. A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").
KEYWORD
word,sign
AUTHOR
Claudio Meller, Aug 26 2009
EXTENSIONS
a(9) corrected, and a(25) and beyond from Michael S. Branicky, Feb 02 2021
STATUS
approved
a(n) is the smallest number whose English name has the letter "i" in the n-th position, or -1 if no such number exists.
+10
8
-1, 5, 13, -1, 1000000, 4000000, 45, 25, 75, 13000000, 17000000, 105, 113, 305, 313, 3013, 145, 125, 175, 325, 375, 3075, 1105, 1113, 1305, 1313, 3305, 1145, 1125, 1175, 1325, 1375, 3325, 3375, 11375, 13325, 13375, 17375, 23325, 23375, 73375, 101375, 103325
OFFSET
1,2
COMMENTS
Original definition used "-2 for infinite".
EXAMPLE
a(2)=5 ("fIve"), a(3)=13 ("thIrteen"), a(5)=10^6 ("onemIllion").
CROSSREFS
Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164792 ("t").
Cf. A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").
KEYWORD
word,sign
AUTHOR
Claudio Meller, Aug 26 2009
EXTENSIONS
a(11) and beyond from Michael S. Branicky, Feb 02 2021
Name changed to remove "-2" (see Comments), and a(1) and a(4) changed from -2 to -1 by Jon E. Schoenfield, Feb 02 2021
STATUS
approved
a(n) is the smallest number whose English name has the letter "f" in the n-th position, or -1 if no such number exists.
+10
8
4, -1, 15, -1, -1, 44, 24, 74, -1, -1, 104, 404, 115, 415, 315, 144, 124, 174, 324, 374, 3074, 1104, 1404, 1115, 1415, 1315, 1144, 1124, 1174, 1324, 1374, 3324, 3374, 11374, 13324, 13374, 17374, 23324, 23374, 73374, 101374, 103324, 103374, 111374, 113324
OFFSET
1,1
EXAMPLE
a(1)=4 ("Four"), a(3)=15 ("fiFteen"), a(11)=104 ("onehundredFour").
CROSSREFS
Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164792 ("t").
Cf. A164793 ("i"), A164795 ("h"), A164796 ("r"), A164797 ("u").
KEYWORD
word,sign
AUTHOR
Claudio Meller, Aug 26 2009
EXTENSIONS
a(21) and beyond from Michael S. Branicky, Feb 02 2021
STATUS
approved
a(n) is the smallest number whose English name has the letter "h" in the n-th position, or -1 if no such number exists.
+10
8
-1, 3, -1, 8, 400, 300, 43, 23, 48, 28, 78, 103, 403, 108, 408, 308, 143, 123, 148, 128, 178, 328, 378, 1403, 1108, 1408, 1308, 1143, 1123, 1148, 1128, 1178, 1328, 1378, 3328, 3378, 11378, 13328, 13378, 17378, 23328, 23378, 73378, 101378, 103328, 103378
OFFSET
1,2
EXAMPLE
a(2)=3 ("tHree"), a(4)=8 ("eigHt"), a(12)=103 ("onehundredtHree").
CROSSREFS
Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164792 ("t").
Cf. A164793 ("i"), A164794 ("f"), A164796 ("r"), A164797 ("u").
KEYWORD
word,sign
AUTHOR
Claudio Meller, Aug 26 2009
EXTENSIONS
a(24) and beyond from Michael S. Branicky, Feb 02 2021
STATUS
approved
a(n) is the smallest number whose English name has the letter "r" in the n-th position, or -1 if no such number exists.
+10
8
-1, -1, 0, 4, 1000000000000, 4000000000000, 3000000000000, 43, 23, 24, 74, 24000000000000, 103, 104, 303, 304, 3004, 143, 123, 124, 174, 324, 374, 1103, 1104, 1303, 1304, 3303, 1143, 1123, 1124, 1174, 1324, 1374, 3324, 3374, 11374, 13324, 13374, 17374, 23324
OFFSET
1,4
EXAMPLE
a(3)=0 ("zeRo"), a(4)=4 ("fouR"), a(5)=1000000000000 ("onetRillion"), a(13)=103 ("onehundredthRee").
CROSSREFS
Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164792 ("t").
Cf. A164793 ("i"), A164794 ("f"), A164795 ("h"), A164797 ("u").
KEYWORD
word,sign
AUTHOR
Claudio Meller, Aug 26 2009
EXTENSIONS
a(24) and beyond from Michael S. Branicky, Feb 02 2021
STATUS
approved

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