OFFSET
1,2
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,4,-4,-6,6,4,-4,-1,1).
FORMULA
From Colin Barker, Dec 17 2015: (Start)
a(n) = 1/2*(200*n^4-920*n^3+1578*n^2-1196*n+338) for n even.
a(n) = 1/2*(200*n^4-520*n^3+498*n^2-208*n+32) for n odd.
G.f.: x*(1+48*x+2972*x^2+3344*x^3+17262*x^4+5648*x^5+8396*x^6+560*x^7+169*x^8) / ((1-x)^5*(1+x)^4).
(End)
MATHEMATICA
Table[SeriesCoefficient[x (1 + 48 x + 2972 x^2 + 3344 x^3 + 17262 x^4 + 5648 x^5 + 8396 x^6 + 560 x^7 + 169 x^8)/((1 - x)^5 (1 + x)^4), {x, 0, n}], {n, 30}] (* Michael De Vlieger, Dec 17 2015 *)
PROG
(PARI) Vec(x*(1+48*x+2972*x^2+3344*x^3+17262*x^4+5648*x^5+8396*x^6+560*x^7+169*x^8) / ((1-x)^5*(1+x)^4) + O(x^40)) \\ Colin Barker, Dec 17 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Erich Friedman.
STATUS
approved