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 A139304 #8 Jul 10 2025 16:00:08 %S A139304 1,256,72057594037927936, %T A139304 452312848583266388373324160190187140051835877600158453279131187530910662656 %N A139304 a(n) = 2^(2p - 1)/32, where p is the n-th Mersenne prime A000668(n). %F A139304 a(n) = 2^(2*A000668(n)-1)/32 = A139294(n)/32. %t A139304 a[n_] := 2^(2^(MersennePrimeExponent[n] + 1) - 8); Array[a, 4] (* _Amiram Eldar_, Jul 10 2025 *) %Y A139304 Cf. A000668, A139294, A139295, A139296, A139297, A139298, A139299, A139300, A139301, A139302, A139303, A139305, A139306. %K A139304 nonn %O A139304 1,2 %A A139304 _Omar E. Pol_, Apr 13 2008 %E A139304 a(4) from _Amiram Eldar_, Jul 10 2025