The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A195335 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A195335

a(n) is the smallest Xmas tree prime with a(n-1) as a prefix (starting with 2).
(history; published version)

#32 by Joerg Arndt at Sun Dec 27 01:57:59 EST 2020

STATUS

reviewed

approved

#31 by Michel Marcus at Sat Dec 26 11:41:04 EST 2020

STATUS

proposed

reviewed

#30 by Michael S. Branicky at Sat Dec 26 11:39:15 EST 2020

STATUS

editing

proposed

#29 by Michael S. Branicky at Sat Dec 26 11:37:19 EST 2020

PROG

(Python)

from sympy import isprime, nextprime

def alst(nn):

alst, astr = [2], "2"

for n in range(2, nn+1):

p = nextprime(10**(n-1))

while not isprime(int(astr + str(p))): p = nextprime(p)

alst.append(int(astr + str(p))); astr += str(p)

return alst

print(alst(11)) # Michael S. Branicky, Dec 26 2020

STATUS

proposed

editing

Discussion

Sat Dec 26

11:39

Michael S. Branicky: Thanks.  Also added a program.

#28 by Michael S. Branicky at Sat Dec 26 11:12:03 EST 2020

STATUS

editing

proposed

#27 by Michael S. Branicky at Sat Dec 26 11:08:03 EST 2020

EXTENSIONS

Name changed corrected by Michael S. Branicky, Dec 26 2020

#26 by Michael S. Branicky at Sat Dec 26 11:07:36 EST 2020

NAME

Smallest a(n) is the smallest Xmas tree prime that has with a(n-1) as a prefix (starting with 2).

EXTENSIONS

Name changed by Michael S. Branicky, Dec 26 2020

STATUS

proposed

editing

#25 by Michael S. Branicky at Sat Dec 26 09:25:11 EST 2020

STATUS

editing

proposed

Discussion

Sat Dec 26

09:45

Michel Marcus: then please add extension: Name corrected by (and system will fill name and date)

09:46

Michel Marcus: and since now name has a(n-1), I would start with "a(n) is the " smallest Xmas tree prime ....

#24 by Michael S. Branicky at Sat Dec 26 09:23:57 EST 2020

NAME

Smallest Xmas tree prime that has a(n-1) as a prefix (starting with k digits where k is the n-th triangular number2).

STATUS

approved

editing

Discussion

Sat Dec 26

09:24

Michael S. Branicky: Data and program fit the revised title; else, an erroneous version of A215641.

#23 by Sean A. Irvine at Sun May 19 03:51:28 EDT 2019

STATUS

reviewed

approved