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 A088506 #10 Jan 28 2022 06:20:54 %S A088506 0,0,1,3,6,30,240,1680,12600,113400,1149120,12640320,151351200, %T A088506 1967565600,27554567040,413318505600,6612836630400,112418222716800, %U A088506 2023536830515200,38447199779788800,768943660374489600,16147816867864281600,355251985172308224000 %N A088506 Number of permutations in the symmetric group S_n that have odd number of transpositions in their cycle decomposition. %H A088506 Alois P. Heinz, <a href="/A088506/b088506.txt">Table of n, a(n) for n = 0..400</a> %F A088506 a(n) = n! - A088336(n). %F A088506 E.g.f.: (1 - exp(-x^2))/(2*(1 - x)). - _Ilya Gutkovskiy_, Jan 23 2018 %Y A088506 Cf. A000142, A088336. %K A088506 nonn %O A088506 0,4 %A A088506 Yuval Dekel (dekelyuval(AT)hotmail.com), Nov 13 2003 %E A088506 More terms from _Alois P. Heinz_, Jun 14 2015