A285792 Primes equal to an octagonal number plus 1.

2, 41, 97, 281, 409, 937, 1409, 2297, 4721, 5209, 6257, 8009, 8641, 12161, 14561, 18097, 21001, 23057, 24121, 26321, 27457, 37409, 42961, 50441, 52009, 55217, 56857, 60209, 70841, 76481, 90481, 139537, 147409, 152777, 161009, 169457, 172321, 227977, 238009

Offset: 1

Author

Colin Barker, Apr 26 2017

Keywords

• nonn

Comments

Primes in A056105. - Omar E. Pol, Apr 26 2017

Links

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

Crossrefs

Cf. A000040, A000567, A002496, A055469, A285789, A285790, A285791.

Programs

Mathematica

Select[PolygonalNumber[8,Range[300]]+1,PrimeQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Oct 22 2017 *)

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(8, k) + 1), listput(L, p))); Vec(L)