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A027930 T(n,2n-7), T given by A027926. 1
1, 3, 8, 21, 54, 133, 309, 674, 1383, 2683, 4950, 8735, 14820, 24285, 38587, 59652, 89981, 132771, 192052, 272841, 381314, 524997, 712977, 956134, 1267395, 1662011, 2157858, 2775763, 3539856, 4477949, 5621943, 7008264 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,2

LINKS

Table of n, a(n) for n=4..35.

Index entries for linear recurrences with constant coefficients, signature (8, -28, 56, -70, 56, -28, 8, -1).

FORMULA

a(n) = sum(binomial(n-k, 7-2k), k=0..3). - Len Smiley, Oct 20 2001

a(n) = C(n,n-1)+C(n+1,n-2)+C(n+2,n-3)+C(n+3,n-4), n>=1. - Zerinvary Lajos, May 29 2007

a(n) = 8*a(n-1) -28*a(n-2) +56*a(n-3) -70*a(n-4) +56*a(n-5) -28*a(n-6) +8*a(n-7) -a(n-8). G.f.: x^4*(x^2-x+1)*(x^4-4*x^3+7*x^2-4*x+1)/(x-1)^8. - R. J. Mathar, Oct 05 2009

MAPLE

seq(binomial(n, n-1)+binomial(n+1, n-2)+binomial(n+2, n-3)+binomial(n+3, n-4), n=1..32); - Zerinvary Lajos, May 29 2007

MATHEMATICA

Table[Total[Binomial[First[#], Last[#]]&/@Table[{n+i, n-1-i}, {i, 0, 3}]], {n, 35}] (* or *) LinearRecurrence[{8, -28, 56, -70, 56, -28, 8, -1}, {1, 3, 8, 21, 54, 133, 309, 674}, 35] (* Harvey P. Dale, Jun 23 2011 *)

CROSSREFS

Cf. A228074.

Sequence in context: A267946 A166287 A186812 * A038200 A291039 A030015

Adjacent sequences:  A027927 A027928 A027929 * A027931 A027932 A027933

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified November 19 08:40 EST 2018. Contains 317347 sequences. (Running on oeis4.)