A071931 Non-Størmer numbers whose largest prime factor is a Størmer number.

8, 30, 32, 38, 46, 50, 55, 57, 75, 76, 99, 100, 111, 122, 128, 132, 133, 142, 174, 177, 183, 185, 200, 203, 212, 213, 228, 237, 242, 253, 254, 265, 266, 268, 274, 278, 302, 305, 319, 322, 327, 334, 342, 348, 360, 377, 380, 381, 394, 395, 411, 413, 418, 437

Offset: 1

Author

Jason Earls, Jun 14 2002

Keywords

• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A005528, A002312.

Cf. A006530.

Programs

Haskell

a071931 n = a071931_list !! (n-1)
a071931_list = filter f a002312_list where
   f x = 2 * gpf <= a006530 (gpf ^ 2 + 1) where gpf = a006530 x
-- Reinhard Zumkeller, Jun 12 2015

Python

from sympy import factorint
def stormer(n): return max(factorint(n*n + 1)) >= 2*n
def ok(n): return not stormer(n) and stormer(max(factorint(n)))
print(list(filter(ok, range(1, 438)))) # Michael S. Branicky, Aug 30 2021