cp's OEIS Frontend

A270816 For each primary pseudoperfect number n, this sequence gives the sum of (n/p + 1)/p for every prime divisor p of n.

%I A270816 #7 Apr 06 2016 01:54:14
%S A270816 1,3,17,691,17521,824473683,19579678305,
%T A270816 3161039281414579992004338982115
%N A270816 For each primary pseudoperfect number n, this sequence gives the sum of (n/p + 1)/p for every prime divisor p of n.
%F A270816 a(k) = Sum_{prime p|n(k)} (n(k)/p + 1)/p, where n(k) = A054377(k).
%e A270816 Prime factors of 42 are 2, 3 and 7: (42/2 + 1)/2 + (42/3 + 1)/3 + (42/7 + 1)/7 = 11 + 5 + 1 = 17.
%p A270816 with(numtheory): P:=proc(q) local a,b,k,n,x;
%p A270816 x:=[2, 6, 42, 1806, 47058, 2214502422, 52495396602, 8490421583559688410706771261086];
%p A270816 for n from 1 to nops(x) do a:=ifactors(x[n])[2];
%p A270816 b:=add((x[n]/a[k][1]+1)/a[k][1],k=1..nops(a)); print(b);
%p A270816 od; end: P(10^4);
%Y A270816 Cf. A054377, A270815.
%K A270816 nonn,more
%O A270816 1,2
%A A270816 _Paolo P. Lava_, Mar 23 2016