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 A187047 #9 Jul 22 2025 10:39:05 %S A187047 0,0,28,136,360,696,1144,1704,2376,3160,4056,5064,6184,7416,8760, %T A187047 10216,11784,13464,15256,17160,19176,21304,23544,25896,28360,30936, %U A187047 33624,36424,39336,42360,45496,48744,52104,55576,59160 %N A187047 Number of 3-step one or two space at a time bishop's tours on an n X n board summed over all starting positions. %C A187047 Row 3 of A187046 %F A187047 Empirical: a(n) = 56*n^2 - 280*n + 360 for n>3 %e A187047 Some solutions for 4X4 %e A187047 ..0..0..0..0....0..0..1..0....3..0..1..0....0..0..0..0....0..3..0..0.. %e A187047 ..0..0..1..0....0..0..0..0....0..2..0..0....0..0..1..0....0..0..0..0.. %e A187047 ..0..2..0..0....2..0..0..0....0..0..0..0....0..3..0..0....0..0..0..2.. %e A187047 ..3..0..0..0....0..3..0..0....0..0..0..0....2..0..0..0....0..0..1..0.. %K A187047 nonn %O A187047 1,3 %A A187047 _R. H. Hardin_ Mar 02 2011