A064678 Numbers k such that sopf(k) = sopfr(k+1), where sopf(k) = A008472(k) and sopfr(k) = A001414(k).

5, 15, 77, 99, 104, 153, 369, 492, 539, 714, 1330, 2491, 4191, 5405, 5831, 5959, 6556, 6579, 6723, 8463, 9424, 12221, 12351, 12726, 13419, 14587, 21716, 24432, 24880, 24895, 26642, 30267, 31487, 33019, 35456, 38324, 43215, 43802, 44831, 45524

Offset: 1

Author

Jason Earls, Oct 10 2001

Keywords

• easy
• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..500 from Harry J. Smith)

Crossrefs

Cf. A001414 (sopfr), A008472 (sopf).

Programs

PARI

sopf(n)= { local(f,s=0); f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]); return(s) } sopfr(n)= { local(f,s=0); f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]*f[i, 2]); return(s) } { n=0; for (m=1, 10^9, if (sopf(m)==sopfr(m + 1), write("b064678.txt", n++, " ", m); if (n==500, break)) ) } \\ Harry J. Smith, Sep 22 2009