OFFSET
1,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
G.f.: (1 - 2x + 6x^2 - 3x^3 + x^4)*x/(1-x)^5.
a(n) = 1 - (5/12)*n + (3/8)*n^2 - (1/12)*n^3 + (1/8)*n^4. - R. J. Mathar, Sep 18 2008
EXAMPLE
a(5) = 76 = (1, 4, 6, 4, 1) dot (1, 2, 6, 3, 7) = (1 + 8 + 36, + 28 + 3).
a(3) = 11 = sum of row 3 terms of triangle A144334: (4 + 3 + 4).
MATHEMATICA
Table[1-5n/12+3n^2/8-n^3/12+n^4/8, {n, 40}] (* or *) LinearRecurrence[{5, -10, 10, -5, 1}, {1, 3, 11, 32, 76}, 40] (* Harvey P. Dale, Aug 22 2016 *)
PROG
(PARI) a(n)=1-(5/12)*n+(3/8)*n^2-(1/12)*n^3+(1/8)*n^4 \\ Charles R Greathouse IV, Oct 21 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson, Sep 18 2008
EXTENSIONS
Extended by R. J. Mathar, Sep 18 2008
STATUS
approved