A075807 - OEIS

A075807

Numbers n such that n-th prime is palindromic.

1, 2, 3, 4, 5, 26, 32, 36, 42, 43, 65, 71, 74, 76, 129, 134, 138, 139, 157, 158, 1263, 1285, 1293, 1367, 1377, 1483, 1519, 1528, 1583, 1635, 1647, 1682, 1726, 1805, 1814, 1867, 1897, 1917, 1928, 2009, 2060, 2083, 2117, 2196, 2250, 2260, 3255, 3267, 3285

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..10000 (n = 1..781 from Vincenzo Librandi, n = 782..5373 from David A. Corneth)

FORMULA

a(n) = A000720(A002385(n)). - David A. Corneth, Mar 24 2019

EXAMPLE

26th prime is 101, which is palindromic.

MAPLE

test := proc(n) local d; d := convert(ithprime(n), base, 10); return ListTools[Reverse](d)=d; end; a := []; for n from 1 to 4000 do if test(n) then a := [op(a), n]; end; od; a;

MATHEMATICA

Rest[Flatten[Position[Prime[Range[4000]], _?(IntegerDigits[#] == Reverse[ IntegerDigits[#]]&)]]] (* Harvey P. Dale, Jan 26 2014 *)

PROG

(Magma) [n: n in [1..3500] | Intseq(NthPrime(n), 10) eq Reverse(Intseq(NthPrime(n), 10))]; // Vincenzo Librandi, Mar 24 2019

(PARI) isok(n) = my(d=digits(prime(n))); Vecrev(d) == d; \\ Michel Marcus, Mar 24 2019

CROSSREFS

Cf. A000720, A002385, A069217.

Sequence in context: A281588 A088865 A237342 * A124232 A051143 A084853

Adjacent sequences: A075804 A075805 A075806 * A075808 A075809 A075810

KEYWORD

nonn,base

AUTHOR

Jani Melik, Oct 13 2002

EXTENSIONS

Edited by Dean Hickerson, Oct 21 2002

STATUS

approved