%I A108704
%S A108704 1,1,4,18,126,1110,12120,156660,2341500,39701340,752839920,15785181720,
%T A108704 362606123880,9055825538760,244296192460320,7079382509799600,
%U A108704 219321853964413200,7233629128601475600,253054306933115688000
%N A108704 Number of partitions of 112233...nn into n pairs.
%D A108704 Laszlo Lovasz: Combinatorial Problems and Solutions.
%F A108704 E.g.f.= exp(x*x/2)/sqrt(1-2*x)
%e A108704 Partitions of 1122 into 2 pairs: 11 22, 12 12, 12 21, 21 21 = 4 partitions 
               so a(2)=4.
%p A108704 E(x):=exp(x*x/2)/sqrt(1-2*x): f[0]:=E(x): for n from 1 to 30 do f[n]:=diff(f[n-1],
               x) od: x:=0: seq(f[n],n=0..30);
%Y A108704 Cf. A002135.
%Y A108704 Sequence in context: A084661 A112294 A073511 this_sequence A001423 A158341 
               A144272
%Y A108704 Adjacent sequences: A108701 A108702 A108703 this_sequence A108705 A108706 
               A108707
%K A108704 nonn
%O A108704 0,3
%A A108704 Miklos Kristof (kristmikl(AT)freemail.hu), Jun 20 2005