The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A064029 Numbers k such that sopfr(k) = ud(k), where sopfr = A001414 and ud = A034444. 1
 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 (list; graph; refs; listen; history; text; internal format)
 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 8 20:37 EST 2021. Contains 349596 sequences. (Running on oeis4.)