%I A055780
%S A055780 1,7,14,35,57,98,140,210,281,385,490,637,785,980,1176,1428,1681,1995,
%T A055780 2310,2695,3081,3542,4004,4550,5097,5733,6370,7105,7841,8680,9520,
%U A055780 10472,11425,12495,13566,14763,15961,17290,18620,20090,21561,23177
%N A055780 Number of symmetric types of (3,2n)-hypergraphs under action of complementing 
               group C(3,2).
%F A055780 G.f. : -(x^8-9*x^6-5*x^2-1)/(1-x^2)^2/(1-x^4)/(1-x^8).
%e A055780 There are 7 symmetric (3,2)-hypergraphs under action of complementing 
               group C(3,2): {{1,2},{1,2,3}}, {{1,3},{1,2,3}}, {{1,2},{1,3}}, {{2,
               3},{1,2,3}}, {{1,2},{2,3}}, {{1,3},{2,3}}, {{1},{2,3}}.
%p A055780 gf := -(x^8-9*x^6-5*x^2-1)/(1-x^2)^2/(1-x^4)/(1-x^8): s := series(gf, 
               x, 200): for i from 0 to 200 by 2 do printf(`%d,`,coeff(s, x, i)) 
               od:
%Y A055780 Sequence in context: A058530 A134384 A084382 this_sequence A161814 A067048 
               A098328
%Y A055780 Adjacent sequences: A055777 A055778 A055779 this_sequence A055781 A055782 
               A055783
%K A055780 nonn
%O A055780 0,2
%A A055780 Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 13 2000
%E A055780 More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jul 13 2000