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A129368 a(n)=sum{k=floor((n+1)/2)..n, C(2k,k)}. 1
1, 2, 8, 26, 96, 342, 1266, 4678, 17548, 66098, 250854, 956034, 3660190, 14059866, 54176466, 209290554, 810370944, 3143964294, 12219099594, 47564314774, 185410843594, 723668533278, 2827767496998, 11061197519166 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Partial sums of A129369.

LINKS

Table of n, a(n) for n=0..23.

FORMULA

G.f.: (1/(1-x))(1/sqrt(1-4x)-x/sqrt(1-4x^2)); a(n)=sum{k=0..floor(n/2), C(2(n-k),n-k)};

a(n)=sum{k=0..floor(n/2), C(2n-2k,n-k)}; - Paul Barry, Oct 09 2007

MATHEMATICA

Table[Sum[Binomial[2k, k], {k, Floor[(n+1)/2], n}], {n, 0, 30}] (* Harvey P. Dale, Aug 13 2012 *)

CROSSREFS

Sequence in context: A307401 A067855 A301699 * A281345 A128238 A110156

Adjacent sequences:  A129365 A129366 A129367 * A129369 A129370 A129371

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Apr 11 2007

STATUS

approved

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Last modified July 23 22:18 EDT 2019. Contains 325269 sequences. (Running on oeis4.)