OFFSET
1,1
EXAMPLE
a(3)=5 because the 3rd non-prime-power is 12 and its prime factors sum to 5.
PROG
(PARI) distinct(n) = \sum the distinct prime factors of n { local(a, x, m, ln, s); for(m=2, n, s=0; a=ifactord(m); ln=length(a); if(ln > 1, for(x=1, ln, s+=a[x]; ); print1(s", ") ) ) } ifactord(n, m=0) = \distinct prime factors of n { local(f, j, k, flist); flist=[]; f=Vec(factor(n, m)); for(j=1, length(f[1]), flist = concat(flist, f[1][j]) ); return(flist) }
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Aug 21 2005
EXTENSIONS
Edited by Don Reble, Jul 23 2006
STATUS
approved