OFFSET
0,4
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,-1).
FORMULA
G.f.: x^2*(1 + 4*x + 10*x^2 + 20*x^3 + 35*x^4 + 20*x^5 + 39*x^6 + 48*x^7 + 55*x^9 + 32*x^10 + 41*x^11 + 18*x^12 - 2*x^13 - 19*x^15 + 105*x^17 + x^18 + 3*x^19 + 6*x^20 + 10*x^21 + 15*x^22 + 89*x^23 + 19*x^24 + 9*x^25 - 48*x^26)/((1 - x)^2*(1 + x + x^2)^2*(1 + x^3 + x^6)^2).
a(n) = 2*a(n-9) - a(n-18) for n > 18.
MATHEMATICA
LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, -1}, {0, 0, 1, 4, 10, 20, 35, 20, 39, 48, 57, 40, 61, 58, 68, 92, 59, 96, 105}, 58]
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Stefano Spezia, Apr 24 2022
STATUS
approved