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a(n) = A000043(n) - 3.
4

%I #18 Oct 17 2024 08:26:42

%S 0,2,4,10,14,16,28,58,86,104,124,518,604,1276,2200,2278,3214,4250,

%T 4420,9686,9938,11210,19934,21698,23206,44494,86240,110500,132046,

%U 216088,756836,859430,1257784,1398266,2976218,3021374,6972590,13466914,20996008,24036580,25964948

%N a(n) = A000043(n) - 3.

%C 2^a(n)-1 is divisible by 3. For (2^a(n)-1)/3 see A124477.

%C For a(n)/2 see A139481.

%H Amiram Eldar, <a href="/A139480/b139480.txt">Table of n, a(n) for n = 2..48</a>

%t MersennePrimeExponent[Range[2, 48]] - 3 (* _Amiram Eldar_, Oct 17 2024 *)

%Y Cf. A000043, A000668, A124477, A139479, A139481.

%K nonn

%O 2,2

%A _Artur Jasinski_, Apr 22 2008

%E Definition corrected by _Omar E. Pol_, May 23 2008

%E Edited by _N. J. A. Sloane_, May 23 2008

%E a(40)-a(42) from _Amiram Eldar_, Oct 17 2024