A285789 Primes equal to a pentagonal number plus 1.

2, 13, 23, 71, 211, 331, 853, 1163, 1427, 2381, 2753, 3433, 3877, 5923, 6113, 6701, 7741, 8627, 9323, 11311, 12377, 14653, 14951, 17443, 18427, 23003, 27271, 31033, 32341, 32783, 34127, 38321, 43777, 52361, 55201, 56941, 57527, 62323, 64171, 64793, 69877

Offset

1,1

Links

Colin Barker, Table of n, a(n) for n = 1..1000

Mathematica

Select[PolygonalNumber[5, Range[300]]+1, PrimeQ] (* Harvey P. Dale, Dec 04 2024 *)

Prog

(PARI) pg(m, n) = (n^2*(m-2)-n*(m-4))/2 \\ n-th m-gonal number
maxk=300; L=List(); for(k=1, maxk, if(isprime(p=pg(5, k) + 1), listput(L, p))); Vec(L)

Crossrefs

Cf. A000040, A000326, A002496, A055469, A285790, A285791, A285792.

Sequence in context: A243621 A195190 A215390 * A090528 A094535 A372600

Adjacent sequences: A285786 A285787 A285788 * A285790 A285791 A285792

Keyword

nonn

Author

Colin Barker, Apr 26 2017

Status

approved