A345002 - OEIS

%I #7 Jun 05 2021 21:48:25

%S 6,28,171,496,8128,478800,32317272,33550336

%N Numbers k such that A345001(k)/A342001(k) is a positive natural number and a divisor of k.

%H <a href="/index/O#opnseqs">Index entries for sequences where odd perfect numbers must occur, if they exist at all</a>

%o (PARI)

%o A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));

%o A003557(n) = (n/factorback(factorint(n)[, 1]));

%o isA345002(n) = if(1==n,0,my(d=A003415(n), s=sigma(n)+d-(n+n), r=s/(d/A003557(n))); (r>0&&1==denominator(r)&&!(n%r)));

%Y Cf. A000396 (subsequence), A003415, A003557, A342001, A345001.

%Y Cf. also A344755.

%K nonn,more

%O 1,1

%A _Antti Karttunen_, Jun 05 2021