cp's OEIS Frontend

A274872 Number of set partitions of [n] into exactly eight blocks such that all odd elements are in blocks with an odd index and all even elements are in blocks with an even index.

%I A274872 #7 Jul 10 2016 14:44:03
%S A274872 1,4,50,200,1519,6076,36564,146256,770481,3081924,14934774,59739096,
%T A274872 273905827,1095623308,4836291512,19345166048,83144608885,332578435540,
%U A274872 1402399388442,5609597553768,23330003686119,93320014744476,384220628807964,1536882515231856
%N A274872 Number of set partitions of [n] into exactly eight blocks such that all odd elements are in blocks with an odd index and all even elements are in blocks with an even index.
%H A274872 Alois P. Heinz, <a href="/A274872/b274872.txt">Table of n, a(n) for n = 8..1000</a>
%F A274872 G.f.: -x^8/((x-1)*(3*x-1)*(2*x+1)*(2*x-1)*(3*x+1)*(4*x-1)*(x+1)* (12*x^2-1)*(6*x^2-1)*(2*x^2-1)).
%e A274872 a(8) = 1: 1|2|3|4|5|6|7|8.
%e A274872 a(9) = 4: 19|2|3|4|5|6|7|8, 1|2|39|4|5|6|7|8, 1|2|3|4|59|6|7|8, 1|2|3|4|5|6|79|8.
%Y A274872 Column k=8 of A274537.
%K A274872 nonn,easy
%O A274872 8,2
%A A274872 _Alois P. Heinz_, Jul 09 2016