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 A212739 #27 Sep 30 2024 14:22:01 %S A212739 0,1,15,511,65535,33554431,68719476735,562949953421311, %T A212739 18446744073709551615,2417851639229258349412351, %U A212739 1267650600228229401496703205375,2658455991569831745807614120560689151,22300745198530623141535718272648361505980415 %N A212739 a(n) = 2^(n^2) - 1. %C A212739 Number of grains for squared chessboards. %H A212739 Wikipedia, <a href="https://en.wikipedia.org/wiki/Wheat_and_chessboard_problem">Wheat and chessboard problem</a> %F A212739 a(n) = 2^(n^2) - 1 = A002416(n) - 1. - _Omar E. Pol_, Jun 11 2012 %e A212739 For usual 8 X 8 chessboard there are 2^64 - 1 = 18446744073709551615 grains. %p A212739 a:= n-> 2^(n^2)-1: %p A212739 seq(a(n), n=0..15); %t A212739 2^Range[0, 12]^2 - 1 (* _Paul F. Marrero Romero_, Sep 30 2024 *) %Y A212739 Cf. A000225, A002416. %K A212739 nonn %O A212739 0,3 %A A212739 _Jani Melik_, Jun 06 2012 %E A212739 Better name from _Omar E. Pol_, Jun 11 2012