Search: id:A130221
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%I A130221
%S A130221 1,1,2,5,12,37,158,667,2740,13461,74710,412095,2406880,15450541,
%T A130221 103187698,715323395,5236160612,40014337437,318488475658,2637143123027,
%U A130221 22603231117364,201268520010153,1855401760331982,17624602999352535
%N A130221 Number of partitions of n-set in which number of blocks of size 2k is 
               odd (or zero) for every k.
%F A130221 E.g.f.: exp(sinh(x))*Product_{k>0} (1+sinh(x^(2*k)/(2*k)!)).
%e A130221 a(4)=12 because from the 15 (=A000110(4)) partitions of the 4-set {a,
               b,c,d} only the partitions ab|cd, ac|bd and ad|bc do not qualify.
%p A130221 g:=exp(sinh(x))*(product(1+sinh(x^(2*k)/factorial(2*k)), k=1..25)): gser:= 
               series(g,x=0,30): seq(factorial(n)*coeff(gser,x,n),n=0..23); - Emeric 
               Deutsch (deutsch(AT)duke.poly.edu), Aug 28 2007
%Y A130221 Cf. A000110, A102759.
%Y A130221 Sequence in context: A003724 A138314 A115277 this_sequence A036782 A050237 
               A050258
%Y A130221 Adjacent sequences: A130218 A130219 A130220 this_sequence A130222 A130223 
               A130224
%K A130221 easy,nonn
%O A130221 0,3
%A A130221 Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 05 2007, Aug 05 2007
%E A130221 More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 28 2007

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