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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A139228 First differences of perfect numbers A000396. 11
 22, 468, 7632, 33542208, 8556318720, 128848822272, 2305842870701260800, 2658455991569831742348849607813890048, 191561942608236104636337386514471893476304705594327040 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Philippe Ellia, On the distance between perfect numbers, arXiv:1210.0450 [math.NT], 2012. Florian Luca and Carl Pomerance, On the radical of a perfect number, New York Journal of Math., 16 (2010), 23-30. FORMULA a(n) = A000396(n+1) - A000396(n). EXAMPLE a(1) = 22 because 6 and 28 are the first two perfect numbers, and their difference is 28 - 6 = 22. MATHEMATICA Differences[Select[Range[10000], DivisorSigma[1, #] == 2# &]] (* Alonso del Arte, Mar 05 2020 *) CROSSREFS Cf. A000396, A139229, A139230, A139231, A139232, A139233, A139234, A139235, A139236, A139237. Sequence in context: A170741 A218724 A276644 * A240782 A261135 A158535 Adjacent sequences:  A139225 A139226 A139227 * A139229 A139230 A139231 KEYWORD nonn AUTHOR Omar E. Pol, Apr 18 2008 EXTENSIONS More terms from Omar E. Pol, Oct 02 2012 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 September 19 02:54 EDT 2020. Contains 337175 sequences. (Running on oeis4.)