OFFSET
0,2
COMMENTS
The first g.f. gives a 0 between each two terms of the sequence - Colin Barker, Jul 12 2013
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2,0,-2,2,-2,0,2,-1).
FORMULA
G.f.: -(x^8-9*x^6-5*x^2-1)/(1-x^2)^2/(1-x^4)/(1-x^8).
G.f.: -(x^4-9*x^3-5*x-1) / ((x-1)^4*(x+1)^2*(x^2+1)). - Colin Barker, Jul 12 2013
EXAMPLE
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}}.
MAPLE
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:
MATHEMATICA
LinearRecurrence[{2, 0, -2, 2, -2, 0, 2, -1}, {1, 7, 14, 35, 57, 98, 140, 210}, 50] (* Harvey P. Dale, May 15 2020 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vladeta Jovovic, Jul 13 2000
EXTENSIONS
More terms from James A. Sellers, Jul 13 2000
More terms from Colin Barker, Jul 12 2013
STATUS
approved