OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..600 from Harry J. Smith)
EXAMPLE
sopf(689)=66, 2*sopf(690)=66.
PROG
(PARI) sopf(n, s, fac, i) = fac=factor(n); for(i=1, matsize(fac)[1], s=s+fac[i, 1]); return(s);
j=[]; for(n=1, 50000, if(sopf(n)==2*sopf(n+1), j=concat(j, n))); j
(PARI) sopf(n)= { local(f, s=0); f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]); return(s) }
{ n=0; sm=sopf(1); for (m=1, 10^9, sp=sopf(m + 1); if (sm==2*sp, write("b064112.txt", n++, " ", m); if (n==600, break)); sm=sp ) } \\ Harry J. Smith, Sep 07 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Sep 08 2001
STATUS
approved