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A027931 T(n, 2n-8), T given by A027926. 2
1, 2, 5, 13, 34, 88, 221, 530, 1204, 2587, 5270, 10220, 18955, 33775, 58060, 96647, 156299, 246280, 379051, 571103, 843944, 1225258, 1750255, 2463232, 3419366, 4686761, 6348772, 8506630, 11282393, 14822249, 19300198, 24922141 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 4..1000

Index entries for linear recurrences with constant coefficients, signature (9,-36,84,-126,126,-84,36,-9,1).

FORMULA

a(n) = Sum_{k=0..4} binomial(n-k, 8-2*k). - Len Smiley, Oct 20 2001

G.f.: x^4*(1 -7*x +23*x^2 -44*x^3 +55*x^4 -44*x^5 +23*x^6 -7*x^7+ x^8) / (1-x)^9 . - R. J. Mathar, Oct 31 2015

MAPLE

A027931 := proc(n)

    add(binomial(n-k, 8-2*k), k=0..4) ;

end proc: # R. J. Mathar, Oct 31 2015

MATHEMATICA

Sum[Binomial[Range[4, 40] -k, 8-2*k], {k, 0, 4}] (* G. C. Greubel, Sep 27 2019 *)

PROG

(PARI) vector(40, n, sum(k=0, 4, binomial(n+3-k, 8-2*k)) ) \\ G. C. Greubel, Sep 27 2019

(MAGMA) [&+[Binomial(n-k, 8-2*k): k in [0..4]] : n in [4..40]]; // G. C. Greubel, Sep 27 2019

(Sage) [sum(binomial(n-k, 8-2*k) for k in (0..4)) for n in (4..40)] # G. C. Greubel, Sep 27 2019

(GAP) List([4..40], n-> Sum([0..4], k-> Binomial(n-k, 8-2*k)) ); # G. C. Greubel, Sep 27 2019

CROSSREFS

Cf. A027926, A228074.

Sequence in context: A122024 A252932 A318234 * A218481 A267905 A209230

Adjacent sequences:  A027928 A027929 A027930 * A027932 A027933 A027934

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified October 23 17:32 EDT 2019. Contains 328373 sequences. (Running on oeis4.)