login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A187442
A trisection of A001405 (central binomial coefficients): binomial(3*n,floor(3*n/2)), n>=0.
2
1, 3, 20, 126, 924, 6435, 48620, 352716, 2704156, 20058300, 155117520, 1166803110, 9075135300, 68923264410, 538257874440, 4116715363800, 32247603683100, 247959266474052, 1946939425648112, 15033633249770520, 118264581564861424
OFFSET
0,2
COMMENTS
For the trisection of sequences see a comment and a reference under A187357.
FORMULA
a(n) = binomial(3*n,floor(3*n/2)), n>=0.
O.g.f.: G0(x^2) + 3*x*G2(x^2) with G0(x) and G2(x) the o.g.f.s of A187363 and A187365, respectively.
MATHEMATICA
Table[Binomial[3n, Floor[(3n)/2]], {n, 0, 20}] (* Harvey P. Dale, Dec 23 2012 *)
CROSSREFS
A187443 binomial(3*n+1,floor((3*n+1)/2)),
A187444 binomial(3*n+2,floor((3*n+2)/2))/2.
Sequence in context: A325890 A323563 A228750 * A167590 A228884 A138910
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Mar 10 2011
STATUS
approved