cp's OEIS Frontend

A336553 Odd numbers k such that gcd(A336551(k), A326143(k)) is equal to A336551(k).

%I A336553 #7 Jul 29 2020 16:38:18
%S A336553 45,63,99,117,147,153,171,207,261,279,315,325,333,369,387,423,425,477,
%T A336553 495,531,549,585,603,639,657,693,711,725,735,747,765,801,819,847,855,
%U A336553 873,909,925,927,963,981,1017,1025,1035,1071,1125,1143,1179,1197,1233,1251,1287,1305,1325,1341,1359,1395,1413,1449,1467,1503
%N A336553 Odd numbers k such that gcd(A336551(k), A326143(k)) is equal to A336551(k).
%C A336553 Is the intersection with A336554 empty?
%H A336553 Antti Karttunen, <a href="/A336553/b336553.txt">Table of n, a(n) for n = 1..10000</a>
%H A336553 <a href="/index/O#opnseqs">Index entries for sequences where odd perfect numbers must occur, if they exist at all</a>
%o A336553 (PARI)
%o A336553 A007947(n) = factorback(factorint(n)[, 1]);
%o A336553 A326143(n) = (sigma(n)-A007947(n)-n);
%o A336553 A336551(n) = { my(f=factor(n)); for(i=1, #f~, f[i, 2] = f[i, 2]-1); (factorback(f)-1); };
%o A336553 isA336553(n) = if(!(n%2),0, my(u=A336551(n)); (u==gcd(u,A326143(n))));
%Y A336553 Odd terms in A336552.
%Y A336553 Cf. A336554.
%K A336553 nonn
%O A336553 1,1
%A A336553 _Antti Karttunen_, Jul 28 2020