A135592 - OEIS

%I #20 May 12 2023 21:36:40

%S 1,1,2,2,2,3,2,2,2,6,2,7,2,8,8,2,2,10,2,11,11,11,2,12,2,13,2,14,2,1,3,

%T 3,15,15,15,15,3,15,15,15,3,5,3,15,15,15,3,15,3,15,15,15,3,15,15,15,

%U 15,15,3,10,3,15,15,3,15,12,3,15,15,13,3,15,3,15,15,15,15,15,3,15,3,15,3,18

%N a(n) is number of earlier terms equal to number of prime divisors of n.

%C Similar to A125087, but instead of exponents, we use number of prime divisors.

%H Katarzyna Matylla, <a href="/A135592/b135592.txt">Table of n, a(n) for n = 1..1000</a>

%e a(12)=7 because 12 has 2 prime divisors (2 and 3) and there are 7 2's in a(1), a(2), ..., a(11).

%o (Maxima) max:1000; f:makelist(0,i,1,max); apr:makelist(0, i, 1, max); f[1]:1; apr[2]:1; print(1,1); for n:2 through max do block(f[n]:apr[length(ifactors(n))+1], apr[f[n]+1]:apr[f[n]+1]+1);

%Y Cf. A125087, A135591.

%K nonn

%O 1,3

%A _Katarzyna Matylla_, Feb 25 2008