A139236 Second differences of even superperfect numbers A061652.

10, 36, 3984, 57408, 135168, 1073283072, 1152921502459625472, 309485007515502060584828928, 81129019444588191927156162428928, 85070429471267271662301605348656545792

Offset: 1

Author

Omar E. Pol, Apr 18 2008

Keywords

• nonn

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

Crossrefs

Cf. A000668, A019279, A061652, A139228, A139229, A139230, A139231, A139232, A139233, A139234, A139235, A139237.

Programs

Mathematica

Differences[2^(Select[Range[512],PrimeQ[2^#-1]&]-1),2] (* Harvey P. Dale, Oct 15 2017 *)

Formula

a(n) = A139234(n+1) - A139234(n).

Extensions

a(6) corrected and more terms from Joerg Arndt, Jul 09 2017