OFFSET
2,1
LINKS
Andrew Howroyd, Table of n, a(n) for n = 2..200
Index entries for linear recurrences with constant coefficients, signature (189,-10731,173215,-1094856,2420208).
FORMULA
a(n) = 3*n*(61^2*84^(n-2) + 96*7^(n-2) - 396*n*7^(n-2))/121. - Andrew Howroyd, May 10 2020
From Colin Barker, Jul 18 2020: (Start)
G.f.: 6*x^2*(5 + 7*x)*(5 - 196*x - 2401*x^2 + 2058*x^3) / ((1 - 7*x)^3*(1 - 84*x)^2).
a(n) = 189*a(n-1) - 10731*a(n-2) + 173215*a(n-3) - 1094856*a(n-4) + 2420208*a(n-5) for n>6.
(End)
PROG
(PARI) a(n) = {3*n*(61^2*84^(n-2) + 96*7^(n-2) - 396*n*7^(n-2))/121} \\ Andrew Howroyd, May 10 2020
(PARI) Vec(6*x^2*(5 + 7*x)*(5 - 196*x - 2401*x^2 + 2058*x^3) / ((1 - 7*x)^3*(1 - 84*x)^2) + O(x^40)) \\ Colin Barker, Jul 18 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. H. Hardin, Apr 20 2009
EXTENSIONS
Terms a(7) and beyond from Andrew Howroyd, May 09 2020
STATUS
approved