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Search: id:A134463
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| A134463 |
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Values of n such that 5n^2 + 5n + 1 is a palindromic prime. |
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2
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OFFSET
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1,2
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COMMENT
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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(8) > 10^9. [From D. S. McNeil (d.mcneil(AT)qmul.ac.uk), Mar 02 2009]
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LINKS
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Eric Weisstein, Link to a section of The World of Mathematics. Palindromic Prime.
Wikipedia: Centered decagonal number.
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MATHEMATICA
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Do[ f=5k^2+5k+1; If[ PrimeQ[f] && FromDigits[ Reverse[ IntegerDigits[ f ] ] ] == f, Print[ k ] ], {k, 1, 500000} ]
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CROSSREFS
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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: A051152 A042181 A042717 this_sequence A058916 A064612 A005927
Adjacent sequences: A134460 A134461 A134462 this_sequence A134464 A134465 A134466
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KEYWORD
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more,nonn,base
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Oct 26 2007
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EXTENSIONS
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a(6), a(7) from D. S. McNeil (d.mcneil(AT)qmul.ac.uk), Mar 02 2009
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