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 A090347 #4 May 10 2013 12:45:29
%S A090347 1,3,8,5,-156,-1253,48,116937,1236140,-4517689,-317599800,-3473788019,
%T A090347 43408737540,2033846838675,19004486417504,-643679274285679,
%U A090347 -24665731809676452,-135665006897593601,15018201730467027960
%N A090347 Number of labeled trees with n nodes and even number of leaves minus number of labeled trees with n nodes and odd number of leaves.
%F A090347 Sum_{k=0..n} (-1)^k*n!/k!*stirling2(n-2, n-k).
%Y A090347 Cf. A055314.
%K A090347 sign
%O A090347 2,2
%A A090347 _Vladeta Jovovic_, Jan 28 2004