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A071931
Non-Størmer numbers whose largest prime factor is a Størmer number.
2
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
1,1
LINKS
PROG
(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
CROSSREFS
Cf. A006530.
Sequence in context: A189946 A239855 A239029 * A333657 A074670 A092277
KEYWORD
nonn
AUTHOR
Jason Earls, Jun 14 2002
STATUS
approved