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A079590
C(6n+1,n).
2
1, 7, 78, 969, 12650, 169911, 2324784, 32224114, 450978066, 6358402050, 90177170226, 1285063345176, 18385569737808, 263926640438545, 3799541229226200, 54834293825867556, 793067310934426018
OFFSET
0,2
COMMENTS
a(n) is the number of paths from (0,0) to (6n,n) taking north and east steps and avoiding north^{=2}. - Shanzhen Gao, Apr 15 2010
LINKS
FORMULA
a(n) is asymptotic to c*sqrt(n)*(46656/3125)^n with c= 0.5243... [c = 2*3^(3/2)/(5^(3/2)*sqrt(Pi)) = 0.52442324668419795386... - Vaclav Kotesovec, Feb 14 2019]
G.f.: hypergeom([1/3, 1/2, 2/3, 5/6, 7/6], [2/5, 3/5, 4/5, 6/5], (46656/3125)*x). - Robert Israel, Aug 07 2014
MAPLE
seq(binomial(6*n+1, n), n = 1 .. 100); # Robert Israel, Aug 07 2014
MATHEMATICA
Table[Binomial[6 n + 1, n], {n, 0, 20}] (* Vincenzo Librandi, Aug 07 2014 *)
PROG
(Magma) [Binomial(6*n+1, n): n in [0..20]]; // Vincenzo Librandi, Aug 07 2014
CROSSREFS
Cf. A052203.
Sequence in context: A210406 A133272 A186657 * A202755 A280518 A156714
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 26 2003
STATUS
approved