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A264822 Centered 15-gonal (or pentadecagonal) primes. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified January 22 02:46 EST 2022. Contains 350481 sequences. (Running on oeis4.)