A064029 Numbers k such that sopfr(k) = ud(k), where sopfr = A001414 and ud = A034444.

2, 5460, 9240, 253890, 358050, 387090, 395850, 429660, 440895, 458850, 468930, 475020, 529074, 550620, 574770, 629850, 669900, 755820, 788970, 803880, 821100, 828828, 895356, 896610, 948090, 985320, 986700, 1065900, 1123122, 1168860, 1184040, 1279080, 1331330

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..3000

Mathematica

Select[Range[10^6],  Plus @@ Times @@@(f = FactorInteger[#]) == 2^Length@f &] (* Amiram Eldar, Dec 01 2019 *)

Prog

(PARI) sopfr(n, s, fac, i) = fac=factor(n); for(i=1, matsize(fac)[1], s=s+fac[i, 1]*fac[i, 2]); return(s);
isok(k) = sopfr(k) == 2^omega(k);

Crossrefs

Cf. A001414, A034444.

Sequence in context: A262059 A153737 A078933 * A057645 A129060 A190127

Adjacent sequences: A064026 A064027 A064028 * A064030 A064031 A064032

Keyword

nonn

Author

Jason Earls, Sep 12 2001

Status

approved