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 A099983 #9 Oct 16 2024 09:19:48 %S A099983 3,7,17,31,89,127,607,2203,3217,4423,9941,19937,23209,86243,132049, %T A099983 756839,1257787,2976221,6972593,20996011,25964951,32582657,42643801, %U A099983 57885161 %N A099983 Bisection of A000043. %F A099983 a(n) = A000043(2*n). - _Amiram Eldar_, Oct 16 2024 %t A099983 MersennePrimeExponent[Range[2, 48, 2]] (* _Amiram Eldar_, Oct 16 2024 *) %Y A099983 Cf. A000043, A099982. %K A099983 nonn,more %O A099983 1,1 %A A099983 _N. J. A. Sloane_, Nov 19 2004 %E A099983 Offset corrected and a(20)-a(24) added by _Amiram Eldar_, Oct 16 2024