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A027928 a(n) = T(n, 2*n-5), T given by A027926. 2
1, 3, 8, 20, 46, 97, 189, 344, 591, 967, 1518, 2300, 3380, 4837, 6763, 9264, 12461, 16491, 21508, 27684, 35210, 44297, 55177, 68104, 83355, 101231, 122058, 146188, 174000, 205901, 242327, 283744, 330649, 383571, 443072 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 3..1000

Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).

FORMULA

a(n) = (n-2)*(n^4 - 8*n^3 + 39*n^2 - 92*n + 180)/120.

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

G.f.: x^3*(1 - 3*x + 5*x^2 - 3*x^3 + x^4)/(1-x)^6. - Colin Barker, Mar 18 2012

E.g.f.: 3 + x -(360 - 240*x + 60*x^2 - 20*x^3 - x^5)*exp(x)/120. - G. C. Greubel, Sep 06 2019

MAPLE

seq(binomial(n, n-1)+binomial(n+1, n-2)+binomial(n+2, n-3), n=1..35); # Zerinvary Lajos, May 29 2007

MATHEMATICA

CoefficientList[Series[(1-3*x+5*x^2-3*x^3+x^4)/(1-x)^6, {x, 0, 40}], x] (* Vincenzo Librandi, Apr 22 2012 *)

PROG

(MAGMA) [(n-2)*(n^4-8*n^3+39*n^2-92*n+180)/120: n in [3..40]]; // Vincenzo Librandi, Apr 22 2012

(PARI) vector(40, n, m=n+2; n*(m^4 -8*m^3 +39*m^2 -92*m +180)/120) \\ G. C. Greubel, Sep 06 2019

(Sage) [(n-2)*(n^4 -8*n^3 +39*n^2 -92*n +180)/120 for n in (3..40)] # G. C. Greubel, Sep 06 2019

(GAP) List([3..40], n-> (n-2)*(n^4 -8*n^3 +39*n^2 -92*n +180)/120); # G. C. Greubel, Sep 06 2019

CROSSREFS

Cf. A228074, A000045.

Sequence in context: A034504 A191522 A140481 * A026624 A026690 A036676

Adjacent sequences:  A027925 A027926 A027927 * A027929 A027930 A027931

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified November 12 07:03 EST 2019. Contains 329052 sequences. (Running on oeis4.)