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 A275977 #17 Aug 14 2025 17:57:19 %S A275977 4,7,8,2,2,0,2,7,8,8,0,5,4,6,1,2,0,2,9,5,2,8,3,9,2,9,8,6,6,0,0,0,5,9, %T A275977 0,9,7,4,1,4,9,7,1,7,2,4,0,2,2,3,6,5,0,0,8,5,1,3,3,4,5,1,0,9,9,1,8,3, %U A275977 7,8,9,5,0,9,4,2,6,6,2,9,7,0,2,7,8,9,2,7,6,8,6,1,1,2,7,0,7,8,9,4,5,8,6,8,2 %N A275977 Decimal expansion of 2^9689 - 1, the 21st Mersenne prime A000668(21). %H A275977 Arkadiusz Wesolowski, <a href="/A275977/b275977.txt">Table of n, a(n) for n = 2917..5833</a> %H A275977 Wikipedia, <a href="http://en.wikipedia.org/wiki/Mersenne_prime">Mersenne prime</a> %F A275977 2^A000043(21) - 1. %e A275977 47822027880546120295283929866000590974149717240223650085133451099183789... %t A275977 First@RealDigits@N[2^9689 - 1, 100] (* _G. C. Greubel_, Aug 15 2016 *) %t A275977 RealDigits[2^MersennePrimeExponent[21]-1,10,120][[1]] (* _Harvey P. Dale_, Aug 14 2025 *) %o A275977 (Magma) Reverse(Intseq(2^9689-1))[1..105]; %o A275977 (PARI) eval(Vec(Str(2^9689-1)))[1..105] %Y A275977 Cf. A169684 = A000668(11), A169681 = A000668(12), A169685 = A000668(13), A204063 = A000668(14), A248931 = A000668(15), A248932 = A000688(16), A248933 = A000668(17), A248934 = A000668(18), A248935 = A000668(19), A248936 = A000668(20), A275979 = A000668(22), A275980 = A000668(23), A275981 = A000668(24), A275982 = A000668(25), A275983 = A000668(26), A275984 = A000668(27). %K A275977 nonn,cons,easy,fini,full %O A275977 2917,1 %A A275977 _Arkadiusz Wesolowski_, Aug 15 2016