|
%I #11 Mar 21 2021 01:38:13
%S 0,2,3,5,5,7,7,10,8,12,9,15,13,14,15,13,14,17,17,17,18,18,19,20,19,20,
%T 20,21,16,21,22,18,24,26,22,19,24,29,19,22,31,29,21,32,31,26,28,28,33,
%U 35,34,34,37,37,35,34,35,35,36,33,38,38,37,39,42,42,39,46,40,42,48,39,38,46,40,40,47,41,44,46,43,39
%N Number of prime factors in the n-th multiply perfect number, counted with multiplicity: a(n) = bigomega(A007691(n)).
%H Amiram Eldar, <a href="/A342658/b342658.txt">Table of n, a(n) for n = 1..1600</a>
%F a(n) = A001222(A007691(n)).
%F a(n) >= A134740(n).
%t Select[Range[10^6], IntegerQ@ DivisorSigma[-1, #] &] (* or, using the b-file at A007691: *)
%t Map[PrimeOmega, DeleteCases[Import["https://oeis.org/A007691/b007691.txt", "Data"], _?(Length@ # == 0 &)][[1 ;; 82, -1]] ] (* _Michael De Vlieger_, Mar 19 2021 *)
%Y Cf. A001222, A007691.
%Y Cf. also A134740, A342659, A342660.
%K nonn,look
%O 1,2
%A _Antti Karttunen_, Mar 19 2021
|
