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 A134463 Values of n such that 5n^2 + 5n + 1 is a palindromic prime. 1
 1, 4, 5, 565, 475081, 4565455, 4639740, 4623988479 (list; graph; refs; listen; history; text; internal format)
 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 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 10-gonal 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

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Last modified March 29 18:37 EDT 2020. Contains 333117 sequences. (Running on oeis4.)