cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A134462 Centered decagonal palindromic primes; or palindromic primes of the form 5k^2 + 5k + 1.

Original entry on oeis.org

11, 101, 151, 1598951, 1128512158211, 104216919612401, 107635959536701, 106906347292743609601, 165901968762984246868642489267869109561
Offset: 1

Views

Author

Alexander Adamchuk, Oct 26 2007

Keywords

Comments

Sequence is the intersection of the palindromic primes = A002385 = {2, 3, 5, 7, 11, 101, 131, 151, ...} and the centered 10-gonal numbers = A062786 = {1, 11, 31, 61, 101, 151, ...}. Corresponding numbers k such that 5k^2 + 5k + 1 is a term of A134462 are listed in A134463 = {1, 4, 5, 565, 475081, ...}. Note that the first 4 terms of A134463 are palindromic as well.
a(9) > 10^25. - Donovan Johnson, Feb 13 2011
a(10) > 10^39. - Patrick De Geest, May 29 2021

Links

Crossrefs

Cf. A002385 = Palindromic primes.
Cf. A062786 = Centered 10-gonal numbers.
Cf. A090562 = Primes of the form 5k^2 + 5k + 1.
Cf. A090563 = Values of k such that 5k^2 + 5k + 1 is a prime.
Cf. A134463 = Values of k such that 5k^2 + 5k + 1 is a palindromic prime.

Programs

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

Extensions

More terms from Tomas J. Bulka (tbulka(AT)rodincoil.com), Aug 30 2009
a(8) from Donovan Johnson, Feb 13 2011
a(9) from Patrick De Geest, May 29 2021
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