OFFSET
1,2
LINKS
John Cerkan, Table of n, a(n) for n = 1..1657
J. R. Stembridge, Some combinatorial aspects of reduced words in finite Coxeter groups, Trans. Amer. Math. Soc. 349 (1997), no. 4, 1285-1332.
FORMULA
G.f.: (1/2)*(((sqrt(1-4*x)-7)*x - 3*sqrt(1-4*x) + 3)/x^2 + 2/(x-1)). - Harvey P. Dale, Apr 28 2013
Conjecture: 3*(n+1)*a(n) + (-19*n+7)*a(n-1) + (33*n-53)*a(n-2) + (-21*n+61)*a(n-3) + 2*(2*n-9)*a(n-4) = 0. - R. J. Mathar, Aug 20 2013
MATHEMATICA
3#[[2]]-#[[1]]-1&/@Partition[CatalanNumber[Range[0, 30]], 2, 1] (* Harvey P. Dale, Apr 28 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved