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 A225557 #16 Dec 01 2024 05:02:22 %S A225557 1,9,11,13,16,19,21,24,26,29,32,35,38,40,44,46,49,52,55,58 %N A225557 Longest checkmate in king and two bishops versus king endgame on an n X n chessboard. %H A225557 V. Kotesovec, <a href="http://problem64.beda.cz/silo/kotesovec_icga_2001.pdf">King and Two Generalised Knights against King</a>, ICGA Journal, Vol. 24, No. 2, pp. 105-107 (2001) %H A225557 V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Fairy chess endings on an n x n chessboard</a>, Electronic edition of chess booklets by Vaclav Kotesovec, vol. 8, p.225 and 236 (2013), p. 350 and 368 (second edition, 2017). %F A225557 Conjecture: a(n) ~ 11*n/4. %e A225557 Longest win on an 8x8 chessboard: Ka1 Bd1 Bb4 - Kc4, 1.Bb4-d6 Kc4-d5! 2.Bd6-g3 Kd5-c6 3.Ka1-b1 Kc6-d5 4.Kb1-c1 Kd5-c6 5.Kc1-c2 Kc6-d5 6.Kc2-d3! Kd5-e6 7.Kd3-e4! Ke6-e7 8.Ke4-e5 Ke7-d7! 9.Ke5-d5 Kd7-e8 10.Bd1-h5 Ke8-e7 11.Bg3-e5! Ke7-d8 12.Kd5-d6! Kd8-c8! 13.Kd6-c6! Kc8-d8! 14.Be5-f6 Kd8-c8! 15.Bh5-g6 Kc8-b8! 16.Kc6-b6! Kb8-a8 17.Bg6-f5 Ka8-b8! 18.Bf6-e5! Kb8-a8! 19.Bf5-e4#, therefore a(8) = 19. %Y A225557 Cf. A225551, A225552, A225553, A225554, A225555, A225556, A227437. %K A225557 nonn,hard,more %O A225557 3,2 %A A225557 _Vaclav Kotesovec_, May 10 2013 %E A225557 a(21)-a(22) from _Vaclav Kotesovec_, Jan 11 2017