Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #5 Dec 19 2020 07:59:32
%S 0,1,1,2,2,2,1,2,1,3,1,2,2,4,2,2,2,5,2,4,1,3,2,3,3,3,1,8,1,2,1,3,2,2,
%T 2,6,2,2,1,4,1,5,2,2,3,4,1,2,3,3,1,4,1,6,1,6,3,3,2,5,1,2,1,4,2,3,1,4,
%U 2,2,1,2,2,3,2,5,2,4,2,3,1,6,2,2,3,3,2,4,1,3,1,5,2,2,2,4,4,2,3,6,2,2,2,2,2
%N Number of prime divisors of (A019565(n) - 1), counted with multiplicity.
%H Antti Karttunen, <a href="/A339812/b339812.txt">Table of n, a(n) for n = 1..65537</a>
%F a(n) = A001222(A339809(n)) = A001222(A019565(n)-1).
%F a(n) = A001222(A339810(n)).
%o (PARI)
%o A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };
%o A339812(n) = bigomega(A019565(n)-1);
%Y Cf. A001222, A019565, A339809, A339810.
%K nonn
%O 1,4
%A _Antti Karttunen_, Dec 18 2020