A276264 Centered 25-gonal primes.

151, 251, 701, 1951, 3001, 4751, 10151, 12401, 16651, 19501, 28201, 29401, 33151, 38501, 39901, 45751, 56951, 63901, 65701, 81001, 87151, 95701, 104651, 114001, 136501, 144451, 147151, 158201, 178501, 181501, 193751, 219451, 232901, 257401, 275651, 290701, 318001, 322001

Offset: 1

Author

Ilya Gutkovskiy, Aug 26 2016

Keywords

• nonn

Comments

Primes of the form (25*k^2 + 25*k + 2)/2.

Numbers k such that (25*k^2 + 25*k + 2)/2 is prime: 3, 4, 7, 12, 15, 19, 28, 31, 36, 39, 47, 48, 51, 55, 56, 60, 67, 71, 72, 80, 83, 87, 91, ...

Links

• Robert Israel, Table of n, a(n) for n = 1..10000
• OEIS Wiki, Centered polygonal numbers
• Eric Weisstein's World of Mathematics, Centered Polygonal Number
• Index entries for sequences related to centered polygonal numbers

Crossrefs

Cf. A000040, A262221.

Cf. centered k-gonal primes listed in A276261.

Programs

Maple

select(isprime, [seq((25*k^2+25*k+2)/2, k=1..200)]); # Robert Israel, Sep 01 2016

Mathematica

Intersection[Table[(25 k^2 + 25 k + 2)/2, {k, 0, 1000}], Prime[Range[28000]]]

PARI

lista(nn) = for(n=1, nn, if(isprime(p=(25*n^2 + 25*n + 2)/2), print1(p, ", "))); \\ Altug Alkan, Aug 26 2016