The OEIS is supported by the many generous donors to the OEIS 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 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A070311 Numbers n such that sopfr(n) and d(n) are both perfect numbers. 1
 338, 2496, 3520, 153280, 508096, 678592, 1162432, 1461952, 2130112, 2475712, 2595520, 2959552, 3042496, 3388096, 3443392, 3581632, 3733696, 3742912, 3744873, 5713173, 9492309, 11912896, 14767353, 15009472, 18021609, 21703125 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Donovan Johnson, Table of n, a(n) for n = 1..300 PROG (PARI) {for(n=1, 22000000, d=numdiv(n); if(d==sigma(d)-d, s=0; F=factor(n); for(i=1, matsize(F)[1], s=s+F[i, 1]*F[i, 2]); if(s==sigma(s)-s, print1(n, ", "))))} CROSSREFS Cf. A000396, A000005, A001414. Sequence in context: A250802 A186052 A186044 * A205648 A221799 A059976 Adjacent sequences: A070308 A070309 A070310 * A070312 A070313 A070314 KEYWORD nonn AUTHOR Jason Earls, May 10 2002 EXTENSIONS More terms from Klaus Brockhaus, May 15 2002 STATUS approved

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

Last modified December 9 03:46 EST 2023. Contains 367681 sequences. (Running on oeis4.)