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

%I A071931 #15 Aug 30 2021 10:54:02
%S A071931 8,30,32,38,46,50,55,57,75,76,99,100,111,122,128,132,133,142,174,177,
%T A071931 183,185,200,203,212,213,228,237,242,253,254,265,266,268,274,278,302,
%U A071931 305,319,322,327,334,342,348,360,377,380,381,394,395,411,413,418,437
%N A071931 Non-Størmer numbers whose largest prime factor is a Størmer number.
%H A071931 Reinhard Zumkeller, <a href="/A071931/b071931.txt">Table of n, a(n) for n = 1..10000</a>
%o A071931 (Haskell)
%o A071931 a071931 n = a071931_list !! (n-1)
%o A071931 a071931_list = filter f a002312_list where
%o A071931    f x = 2 * gpf <= a006530 (gpf ^ 2 + 1) where gpf = a006530 x
%o A071931 -- _Reinhard Zumkeller_, Jun 12 2015
%o A071931 (Python)
%o A071931 from sympy import factorint
%o A071931 def stormer(n): return max(factorint(n*n + 1)) >= 2*n
%o A071931 def ok(n): return not stormer(n) and stormer(max(factorint(n)))
%o A071931 print(list(filter(ok, range(1, 438)))) # _Michael S. Branicky_, Aug 30 2021
%Y A071931 Cf. A005528, A002312.
%Y A071931 Cf. A006530.
%K A071931 nonn
%O A071931 1,1
%A A071931 _Jason Earls_, Jun 14 2002