cp's OEIS Frontend

A336552 Numbers k such that A003557(k)-1 either divides A326143(k) [= A001065(k) - A007947(k)], or both are zero. Numbers k such that gcd(A336551(k), A326143(k)) is equal to A336551(k).

%I A336552 #8 Jul 29 2020 16:38:11
%S A336552 4,6,12,20,24,28,44,45,48,52,60,63,68,76,84,90,92,96,99,116,117,120,
%T A336552 124,126,132,140,144,147,148,150,153,156,164,168,171,172,188,192,198,
%U A336552 204,207,212,220,228,234,236,244,260,261,264,268,272,276,279,284,292,294,306,308,312,315,316,325,332,333,340,342,348,350
%N A336552 Numbers k such that A003557(k)-1 either divides A326143(k) [= A001065(k) - A007947(k)], or both are zero. Numbers k such that gcd(A336551(k), A326143(k)) is equal to A336551(k).
%C A336552 Numbers k such that either A336551(k) and A326143(k) are both zero (in which case k is squarefree), or A336551(k) divides A326143(k) (in which case k is not squarefree).
%H A336552 Antti Karttunen, <a href="/A336552/b336552.txt">Table of n, a(n) for n = 1..10000</a>
%o A336552 (PARI)
%o A336552 A007947(n) = factorback(factorint(n)[, 1]);
%o A336552 A326143(n) = (sigma(n)-A007947(n)-n);
%o A336552 A336551(n) = { my(f=factor(n)); for(i=1, #f~, f[i, 2] = f[i, 2]-1); (factorback(f)-1); };
%o A336552 isA336552(n) = { my(u=A336551(n)); (u==gcd(u,A326143(n))); };
%Y A336552 Cf. A007947, A326143, A336550, A336551, A336553 (odd terms).
%K A336552 nonn
%O A336552 1,1
%A A336552 _Antti Karttunen_, Jul 28 2020