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 A285875 #8 Apr 17 2022 01:01:38 %S A285875 1,18,324,6572,132640,3030492,68633066,1733220521,43321058602, %T A285875 1182486223832 %N A285875 Number of possible chess games at the end of the n-th ply starting without knights. %C A285875 Gives the number of possible chess games where both sides start without knights. Knights are still allowed to appear later in the game through promotion. %C A285875 Does not include games which end in fewer than n plies. %C A285875 The total number of such games should be less than the total number of standard chess games, and it appears A285875(n) <= A048987(n) for all n. %C A285875 Initial terms computed using the Chesspresso engine. %H A285875 <a href="http://www.chesspresso.org/">Chesspresso<sup>TM</sup></a>. %e A285875 a(1) = 18 because each pawn can move forward 1 or 2 squares (16 moves) and each rook can move into the square where the knight would have been (2 moves). %Y A285875 Cf. A048987 (standard), A285873 (no queens), A285874 (no rooks), A285876 (no bishops), A285877 (no pawns), A285878 (pawns and king). %K A285875 nonn,hard,more,fini %O A285875 0,2 %A A285875 _Sean A. Irvine_, Apr 28 2017