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 A139236 Second differences of even superperfect numbers A061652. 11
 10, 36, 3984, 57408, 135168, 1073283072, 1152921502459625472, 309485007515502060584828928, 81129019444588191927156162428928, 85070429471267271662301605348656545792 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Second differences of Mersenne primes A000668, divided by 2 (see A139232). Also, second differences of superperfect numbers A019279, if there are no odd superperfect numbers. LINKS Jinyuan Wang, Table of n, a(n) for n = 1..16 FORMULA a(n) = A139234(n+1) - A139234(n). MATHEMATICA Differences[2^(Select[Range[512], PrimeQ[2^#-1]&]-1), 2] (* Harvey P. Dale, Oct 15 2017 *) CROSSREFS Cf. A000668, A019279, A061652, A139228, A139229, A139230, A139231, A139232, A139233, A139234, A139235, A139237. Sequence in context: A220199 A089222 A139242 * A212795 A227695 A247792 Adjacent sequences:  A139233 A139234 A139235 * A139237 A139238 A139239 KEYWORD nonn AUTHOR Omar E. Pol, Apr 18 2008 EXTENSIONS a(6) corrected and more terms from Joerg Arndt, Jul 09 2017 STATUS approved

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Last modified September 20 19:32 EDT 2020. Contains 337265 sequences. (Running on oeis4.)