OFFSET
0,3
LINKS
Giovanni Resta, Table of n, a(n) for n = 0..322 (first 101 terms from Harry J. Smith)
MATHEMATICA
a[n_] := If[n < 2, 0, Total[Times @@@ FactorInteger[Floor[10^n/9]]]]; Array[a, 30, 0] (* Giovanni Resta, Jul 19 2018 *)
PROG
(PARI) a(n) = (10^n-1)/9; {sopfr(n, s, fac, i) = fac=factor(n); for(i=1, matsize(fac)[1], s=s+fac[i, 1]*fac[i, 2]); return(s); } for(n=0, 35, print1(sopfr(a(n)), ", "))
(PARI) sopfr(n)= { local(f, s=0); f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]*f[i, 2]); return(s) } { for (n=0, 100, write("b064798.txt", n, " ", sopfr((10^n - 1)/9)) ) } \\ Harry J. Smith, Sep 26 2009
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jason Earls, Oct 18 2001
STATUS
approved