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
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
KEYWORD
nonn,easy
AUTHOR
STATUS
approved