%I #13 Oct 21 2024 04:35:54
%S 0,0,1,2,7,10,11,22,51,78,95,114,507,592,1263,2186,2263,3198,4233,
%T 4402,9667,9918,11189,19912,21675,23182,44469,86214,110473,132018,
%U 216059,756806,859399,1257752,1398233,2976184,3021339,6972554,13466877
%N Base-2 logarithm of (n-th even superperfect number divided by 2^n).
%H Amiram Eldar, <a href="/A134712/b134712.txt">Table of n, a(n) for n = 1..48</a>
%H Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y perfectos</a>.
%F a(n) = log_2(A061652(n)/(2^n)) = A000043(n) - n - 1 = A090748(n) - n.
%e a(5) = 7 because the 5th even superperfect number is 4096, 2^5 = 32, 4096/32 = 128 and log_2(128) = 7 (because 2^7 = 128).
%t With[{max = 48}, MersennePrimeExponent[Range[max]] - Range[max] - 1] (* _Amiram Eldar_, Oct 21 2024 *)
%Y Cf. A000043, A000396, A000668, A019279, A061652, A090748, A133028.
%K nonn,changed
%O 1,4
%A _Omar E. Pol_, Nov 07 2007