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 A248936 #15 Sep 08 2022 08:46:10 %S A248936 2,8,5,5,4,2,5,4,2,2,2,8,2,7,9,6,1,3,9,0,1,5,6,3,5,6,6,1,0,2,1,6,4,0, %T A248936 0,8,3,2,6,1,6,4,2,3,8,6,4,4,7,0,2,8,8,9,1,9,9,2,4,7,4,5,6,6,0,2,2,8, %U A248936 4,4,0,0,3,9,0,6,0,0,6,5,3,8,7,5,9,5,4,5,7,1,5,0,5,5,3,9,8,4,3,2,3,9,7,5,4 %N A248936 Decimal expansion of 2^4423 - 1, the 20th Mersenne prime A000668(20). %C A248936 The 19th Mersenne prime and this prime were found in 1961 by Alexander Hurwitz, using IBM 7090. %H A248936 Arkadiusz Wesolowski, <a href="/A248936/b248936.txt">Table of n, a(n) for n = 1332..2663</a> %H A248936 Alexander Hurwitz, <a href="http://www.ams.org/journals/mcom/1962-16-078/S0025-5718-1962-0146162-X/S0025-5718-1962-0146162-X.pdf">New Mersenne Primes</a>, Mathematics of Computation, vol. 16, No. 78 (1962), pp. 249-251. %H A248936 Wikipedia, <a href="http://en.wikipedia.org/wiki/Mersenne_prime">Mersenne prime</a> %F A248936 Equals 2^A000043(20) - 1. %e A248936 28554254222827961390156356610216400832616423864470288919924745660228440... %t A248936 RealDigits[2^4423 - 1, 10, 100][[1]] (* _G. C. Greubel_, Oct 03 2017 *) %o A248936 (Magma) Reverse(Intseq(2^4423-1)); %o A248936 (PARI) eval(Vec(Str(2^4423-1))) %Y A248936 Cf. A169684 = A000668(11), A169681 = A000668(12), A169685 = A000668(13), A204063 = A000668(14), A248931 = A000668(15), A248932 = A000668(16), A248933 = A000668(17), A248934 = A000668(18), A248935 = A000668(19). %K A248936 nonn,cons,easy,fini,full %O A248936 1332,1 %A A248936 _Arkadiusz Wesolowski_, Oct 17 2014