OFFSET
0,2
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,2,-2,0,-1,1).
FORMULA
From Colin Barker, Jan 15 2018: (Start)
G.f.: (1 + 3*x + 6*x^2 + 13*x^3 + 18*x^4 + 6*x^5 + 4*x^6 + 3*x^7) / ((1 - x)^3*(1 + x + x^2)^2).
a(n) = a(n-1) + 2*a(n-3) - 2*a(n-4) - a(n-6) + a(n-7) for n>7.
(End)
MATHEMATICA
LinearRecurrence[{1, 0, 2, -2, 0, -1, 1}, {1, 4, 10, 25, 49, 67, 100, 148}, 60] (* Harvey P. Dale, Apr 30 2023 *)
PROG
(PARI) Vec((1 + 3*x + 6*x^2 + 13*x^3 + 18*x^4 + 6*x^5 + 4*x^6 + 3*x^7) / ((1 - x)^3*(1 + x + x^2)^2) + O(x^50)) \\ Colin Barker, Jan 15 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Chaim Goodman-Strauss and N. J. A. Sloane, Jan 13 2018
STATUS
approved