This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A139481 #19 Oct 17 2024 12:16:01 %S A139481 0,1,2,5,7,8,14,29,43,52,62,259,302,638,1100,1139,1607,2125,2210,4843, %T A139481 4969,5605,9967,10849,11603,22247,43120,55250,66023,108044,378418, %U A139481 429715,628892,699133,1488109,1510687,3486295,6733457,10498004,12018290 %N A139481 a(n) = A139480(n)/2. %H A139481 Amiram Eldar, <a href="/A139481/b139481.txt">Table of n, a(n) for n = 2..48</a> %F A139481 a(n) = A146768(n-1)-1. - _R. J. Mathar_, Mar 30 2011 %t A139481 (MersennePrimeExponent[Range[2, 48]] - 3)/2 (* _Amiram Eldar_, Oct 17 2024 *) %Y A139481 Cf. A000043, A000668, A124477, A139479, A139480, A146768. %K A139481 nonn,less %O A139481 2,3 %A A139481 _Artur Jasinski_, Apr 22 2008 %E A139481 Edited by _N. J. A. Sloane_, May 23 2008