A050368 Number of ways to factor n into distinct factors with 2 kinds of 2, 3 kinds of 3, ...
1, 2, 3, 5, 5, 12, 7, 16, 12, 20, 11, 39, 13, 28, 30, 42, 17, 60, 19, 65, 42, 44, 23, 126, 35, 52, 55, 91, 29, 150, 31, 116, 66, 68, 70, 219, 37, 76, 78, 210, 41, 210, 43, 143, 150, 92, 47, 378, 70, 170, 102, 169, 53, 290, 110, 294, 114, 116, 59, 570, 61, 124, 210
Offset: 1
Keywords
Links
- Andrew Howroyd, Table of n, a(n) for n = 1..1000
Programs
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PARI
seq(n)={my(v=vector(n, k, k==1)); for(k=2, n, my(m=logint(n,k), p=(1 + x + O(x*x^m))^k, w=vector(n)); for(i=0, m, w[k^i]=polcoef(p,i)); v=dirmul(v,w)); v} \\ Andrew Howroyd, Oct 27 2019
Formula
Dirichlet g.f.: Product_{n>=2}((1+1/n^s)^n).