A264822 Centered 15-gonal (or pentadecagonal) primes.

151, 421, 541, 991, 1171, 1801, 2851, 6091, 11701, 12301, 14851, 16921, 19891, 30241, 34171, 42751, 43891, 52291, 53551, 58741, 62791, 64171, 80341, 81901, 93241, 107101, 121921, 131671, 156601, 163171, 165391, 183691, 193201, 210421, 231001, 233641, 241651, 244351

Offset

1,1

Comments

Primes of the form (15*k^2 - 15*k + 2)/2.

All the terms in this sequence are congruent to 1 (mod 10). - K. D. Bajpai, Nov 29 2015

The associated k-values are 5, 8, 9, 12, 13, 16, 20, 29, 40, 41, 45, 48, 52, 64, 68, 76, 77, 84, 85, 89, ... - Danny Rorabaugh, Jan 18 2016

Links

K. D. Bajpai, Table of n, a(n) for n = 1..10000

OEIS Wiki, Figurate numbers

Eric Weisstein's World of Mathematics, Centered Polygonal Number and Prime Number

Maple

select(isprime, [seq((15*k^2 - 15*k + 2) / 2, k=0..1000)]); # K. D. Bajpai, Nov 29 2015

Mathematica

Select[Table[(15n^2 - 15n + 2) / 2, {n, 500}], PrimeQ] (* K. D. Bajpai, Nov 29 2015 *)

Prog

(PARI) for(n=1, 1e3, if(isprime(k=(15*n^2-15*n+2)/2), print1(k, ", "))) \\ Altug Alkan, Nov 26 2015
(Magma) [k: n in [1..10000] | IsPrime(k) where k is (15*n^2-15*n+2) div 2]; // K. D. Bajpai, Nov 29 2015

Crossrefs

Cf. A000040, A069128.

Sequence in context: A089317 A141982 A142271 * A002226 A142361 A142506

Adjacent sequences: A264819 A264820 A264821 * A264823 A264824 A264825

Keyword

nonn

Author

Ilya Gutkovskiy, Nov 26 2015

Status

approved