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 A263690 #13 Apr 10 2020 16:18:46 %S A263690 1,1,2,6,24,36,36,48,80,128,200,288,432,648,992,1496,2272,3424,5192, %T A263690 7840,11880,17952,27184,41096,62208,94072,142368,215328,325832,492864, %U A263690 745736,1128096,1706800,2582024,3906464,5909784,8941024,13526368,20464072,30959200 %N A263690 Number of length n arrays of permutations of 0..n-1 with each element moved by -n to n places and every three consecutive elements having its maximum within 3 of its minimum. %H A263690 Alois P. Heinz, <a href="/A263690/b263690.txt">Table of n, a(n) for n = 0..5558</a> %F A263690 Empirical: a(n) = a(n-1) +a(n-2) -a(n-3) +a(n-4) for n>12. %F A263690 G.f.: (8*x^12+8*x^11-4*x^10-8*x^8+6*x^7+20*x^6-7*x^5-16*x^4-4*x^3-1) / (x^4-x^3+x^2+x-1). - _Alois P. Heinz_, Apr 08 2020 %Y A263690 Diagonal of A263693. %Y A263690 Cf. A333833. %K A263690 nonn,easy %O A263690 0,3 %A A263690 _R. H. Hardin_, Oct 23 2015 %E A263690 a(0), a(24)-a(39) from _Alois P. Heinz_, Apr 08 2020