A285792 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

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

LINKS

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

MATHEMATICA

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

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