

A134463


Values of n such that 5n^2 + 5n + 1 is a palindromic prime.


1




OFFSET

1,2


COMMENTS

Corresponding Centered decagonal palindromic primes are 5a(n)^2 + 5a(n) + 1 = A134462 = {11,101,151,1598951,1128512158211, ...}. Note that the first 4 terms of a(n) are the palindromes.
a(9) > 1414213562372.  Donovan Johnson, Feb 13 2011


LINKS

Table of n, a(n) for n=1..8.
Eric Weisstein's World of Mathematics, Palindromic Prime
Wikipedia, Centered decagonal number.


MATHEMATICA

Do[ f=5k^2+5k+1; If[ PrimeQ[f] && FromDigits[ Reverse[ IntegerDigits[ f ] ] ] == f, Print[ k ] ], {k, 1, 500000} ]


CROSSREFS

Cf. A134462 = Centered decagonal palindromic primes; or palindromic primes of the form 5n^2 + 5n + 1. Cf. A002385 = Palindromic primes. Cf. A062786 = Centered 10gonal numbers. Cf. A090562 = Primes of the form 5k^2 + 5k + 1. Cf. A090563 = Values of n such that 5n^2 + 5n + 1 is a prime.
Sequence in context: A042181 A042717 A304286 * A298938 A309071 A270975
Adjacent sequences: A134460 A134461 A134462 * A134464 A134465 A134466


KEYWORD

more,nonn,base


AUTHOR

Alexander Adamchuk, Oct 26 2007


EXTENSIONS

a(6), a(7) from D. S. McNeil, Mar 02 2009
a(8) from Donovan Johnson, Feb 13 2011


STATUS

approved



