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 A186852 #14 Jan 07 2023 20:09:53 %S A186852 16,104,328,664,1112,1672,2344,3128,4024,5032,6152,7384,8728,10184, %T A186852 11752,13432,15224,17128,19144,21272,23512,25864,28328,30904,33592, %U A186852 36392,39304,42328,45464,48712,52072,55544,59128,62824,66632,70552,74584,78728,82984,87352 %N A186852 Number of 3-step knight's tours on an (n+2) X (n+2) board summed over all starting positions. %H A186852 Andrew Howroyd, <a href="/A186852/b186852.txt">Table of n, a(n) for n = 1..1000</a> %F A186852 Empirical: a(n) = 56*n^2 - 56*n - 8 for n > 1. %F A186852 The above empirical formula is correct. See A186851 for details. - _Andrew Howroyd_, Jan 07 2023 %e A186852 Some solutions for 5 X 5: %e A186852 0 0 0 0 0 3 0 0 0 0 0 0 0 3 0 0 0 3 0 0 %e A186852 0 1 0 0 0 0 0 2 0 0 0 2 0 0 0 0 1 0 0 0 %e A186852 0 0 0 2 0 0 0 0 0 1 0 0 0 0 0 0 0 0 2 0 %e A186852 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 %e A186852 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 %o A186852 (PARI) row(3, 40) \\ row(m, n) defined in A186851. - _Andrew Howroyd_, Jan 07 2023 %Y A186852 Row 3 of A186851. %K A186852 nonn %O A186852 1,1 %A A186852 _R. H. Hardin_, Feb 27 2011 %E A186852 Terms a(27) and beyond from _Andrew Howroyd_, Jan 07 2023