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 A005777 M3544 #22 Jul 08 2025 16:35:39 %S A005777 1,4,18,96,265,672,1617,3776,8577,19080,41745,90048,191945,404992, %T A005777 846945,1757440,3621697,7417800,15109313,30623520,61788489,124158496, %U A005777 248549937,495852480,986076225,1955203016,3866245425,7625813888,15005718153 %N A005777 Rook polynomials. %D A005777 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A005777 Earl Glen Whitehead, Jr., <a href="http://dx.doi.org/10.1017/S1446788700012337">Four-discordant permutations</a>, J. Austral. Math. Soc. Ser. A 28 (1979), no. 3, 369-377. %F A005777 Conjecture: G.f.: x + 4*x^2 - 15*x^3 + x^3*((33 - 69*x + 16*x^2 - 14*x^3 + 82*x^4 - 8*x^5 - 20*x^6 - 38*x^7 + 9*x^8 + 9*x^9 + 8*x^10) / ((1 - x)^2 * (1 - x - x^2 - x^3)^3)). - _Vaclav Kotesovec_, Aug 27 2016 %Y A005777 A diagonal of A259985. %K A005777 nonn %O A005777 1,2 %A A005777 _N. J. A. Sloane_ %E A005777 More terms from _Sean A. Irvine_, Aug 27 2016