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 A056174 #7 Apr 15 2022 23:39:52 %S A056174 0,0,0,10,190,2878,45738,820118,16764354,387371878,9999815254, %T A056174 285310965190,8916097744112,302875096191666,11112006785441430, %U A056174 437893890225741870,18446744073108471242,827240261884003157974,39346408075287462440142,1978419655660278243860198 %N A056174 Number of non-monotone maps from 1,...,n to 1,...,n. %F A056174 a(n) = n^n - C(2n, n) + n = A000312(n) - A045992(n) %e A056174 a(3)=10 since the mappings of (1,2,3) to (1,2,1), (1,3,1), (1,3,2), (2,1,2), (2,1,3), (2,3,1), (2,3,2), (3,1,2), (3,1,3) and (3,2,3) all reverse direction %Y A056174 Cf. A000312, A000984, A001700, A045992. %K A056174 nonn %O A056174 0,4 %A A056174 _Henry Bottomley_, Jul 27 2000 %E A056174 More terms from _Sean A. Irvine_, Apr 15 2022