cp's OEIS Frontend

A337543 Numbers that are in A337381, but that have no proper divisor in A337381.

%I A337543 #6 Aug 31 2020 10:23:31
%S A337543 6,8,9,14,15,20,21,35,44,49,50,52,68,76,92,110,124,125,130,148,172,
%T A337543 188,190,212,230,244,275,286,292,310,325,338,356,363,425,429,452,470,
%U A337543 475,494,507,575,598,627,663,715,741,759,775,806,845,847,874,897,925,969,1001,1023,1058,1075,1083,1131,1173,1175,1183,1209
%N A337543 Numbers that are in A337381, but that have no proper divisor in A337381.
%C A337543 Numbers k that are in A337381 [i.e., for which A003973(k) >= 2*A000203(k)], but none of whose proper divisors are in A337381.
%H A337543 Antti Karttunen, <a href="/A337543/b337543.txt">Table of n, a(n) for n = 1..20000</a>
%H A337543 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H A337543 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A337543 {k: 1==A337541(k)}.
%o A337543 (PARI)
%o A337543 A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
%o A337543 A337541(n) = sumdiv(n,d,sigma(A003961(d))>=2*sigma(d));
%o A337543 isA337543(n) = (1==A337541(n));
%Y A337543 Cf. A000203, A003961, A003973, A337381, A337383, A337541, A337542.
%Y A337543 Cf. also A091191, A337372.
%K A337543 nonn
%O A337543 1,1
%A A337543 _Antti Karttunen_, Aug 31 2020