%I A090748
%S A090748 1,2,4,6,12,16,18,30,60,88,106,126,520,606,1278,2202,2280,3216,4252,
%T A090748 4422,9688,9940,11212,19936,21700,23208,44496,86242,110502,132048,
%U A090748 216090,756838,859432,1257786,1398268,2976220,3021376,6972592,13466916
%N A090748 Numbers n such that 2^(n+1) - 1 is prime.
%C A090748 Perfect numbers A000396(n) = 2^A133033(n) - 2^a(n), assuming there are
no odd perfect numbers. - Omar E. Pol (info(AT)polprimos.com), Feb
24 2008
%C A090748 Number of proper divisors of n-th even perfect number that are multiples
of n-th Mersenne prime A000668(n). - Omar E. Pol (info(AT)polprimos.com),
Feb 28 2008
%C A090748 Base 2 logarithm of n-th even superperfect number A061652(n). Also base
2 logarithm of n-th superperfect number A019279(n), assuming there
are no odd superperfect numbers. - Omar E. Pol (info(AT)polprimos.com),
Apr 11 2008
%C A090748 Number of 0's in binary expansion of n-th even perfect number (See A135650).
- Omar E. Pol (info(AT)polprimos.com), May 04 2008
%H A090748 O. E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica
de los numeros primos y perfectos</a>.
%e A090748 a(1) = 1 because 2^2 - 1 = 3 is prime
%t A090748 lst={};Do[If[PrimeQ[2^(n+1)-1], AppendTo[lst, n]], {n, 10^5}];lst [From
Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 21 2008]
%Y A090748 a(n) = A000043(n) - 1. A000043 is the main entry for this sequence.
%Y A090748 Cf. A000396, A133033, A000668.
%Y A090748 Cf. A019279, A061652.
%Y A090748 Cf. A135650.
%Y A090748 Sequence in context: A141113 A050584 A019280 this_sequence A032465 A089395
A089699
%Y A090748 Adjacent sequences: A090745 A090746 A090747 this_sequence A090749 A090750
A090751
%K A090748 nonn
%O A090748 1,2
%A A090748 Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Feb 03 2004
%E A090748 Edited, corrected and extended by Robert G. Wilson v (rgwv(AT)rgwv.com),
Feb 09 2004
%E A090748 Updated (a(39)) by Omar E. Pol (info(AT)polprimos.com), Jan 23 2009
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