OFFSET
0,1
COMMENTS
Related to A000699, the number of irreducible diagrams with 2n nodes.
FORMULA
a(n) = A000699(n+1)*(2*n+3)*(n+2)/(3*(n+1)).
CROSSREFS
KEYWORD
nonn
AUTHOR
Philippe Deléham and Paul D. Hanna, Nov 03 2005
STATUS
approved