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 A115278 #8 Jan 22 2016 08:06:45
%S A115278 1,1,1,16,29,256,14422,49141,490429,10758400,1797335306,9458619391,
%T A115278 133756636598,2528529510391,137864810180749,53441183229799381,
%U A115278 410251032050409469,7615997734377068128,167055180095977694194,6741819165851219788075,738863335901972011745434
%N A115278 Number of partitions of {1,...,2*n} into even sized blocks such that no block size is repeated.
%H A115278 Alois P. Heinz, <a href="/A115278/b115278.txt">Table of n, a(n) for n = 0..370</a>
%F A115278 E.g.f.: B(x) of b(n) where b(2*n)=a(n), b(2*n+1)=0. B(x)=Product {m >= 1} (1+x^(2*m)/(2*m)!).
%p A115278 with(combinat):
%p A115278 b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0, add(
%p A115278 multinomial(n, n-i*j, i$j)/j!*b(n-i*j, i-2), j=0..min(1, n/i))))
%p A115278 end:
%p A115278 a:= n-> b(2*n$2):
%p A115278 seq(a(n), n=0..30); # _Alois P. Heinz_, Mar 08 2015
%t A115278 multinomial[n_, k_List] := n!/Times @@ (k!); b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, Sum[multinomial[n, Join[{n - i*j}, Array[i &, j]]]/j!* b[n - i*j, i - 2], {j, 0, Min[1, n/i]}]]]; a[n_] := b[2 n, 2 n]; Table[ a[n], {n, 0, 30}] (* _Jean-François Alcover_, Jan 22 2016, after _Alois P. Heinz_ *)
%Y A115278 Cf. A005046, A007837, A032310, A115277.
%K A115278 nonn
%O A115278 0,4
%A A115278 _Christian G. Bower_, Jan 18 2006