cp's OEIS Frontend

A274873 Number of set partitions of [n] into exactly nine 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 A274873 #7 Jul 10 2016 14:43:20
%S A274873 1,4,70,280,2919,11676,94944,379776,2669361,10677444,68321994,
%T A274873 273287976,1640345707,6561382828,37643205652,150572822608,
%U A274873 836008721925,3344034887700,18122573826942,72490295307768,385781480224959,1543125920899836,8099850233307144
%N A274873 Number of set partitions of [n] into exactly nine 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 A274873 Alois P. Heinz, <a href="/A274873/b274873.txt">Table of n, a(n) for n = 9..1000</a>
%F A274873 G.f.: x^9/((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)*(20*x^2-1)*(2*x^2-1)).
%e A274873 a(9) = 1: 1|2|3|4|5|6|7|8|9.
%e A274873 a(10) = 4: 1|2(10)|3|4|5|6|7|8|9, 1|2|3|4(10)|5|6|7|8|9, 1|2|3|4|5|6(10)|7|8|9, 1|2|3|4|5|6|7|8(10)|9.
%Y A274873 Column k=9 of A274537.
%K A274873 nonn,easy
%O A274873 9,2
%A A274873 _Alois P. Heinz_, Jul 09 2016