OFFSET
0,3
COMMENTS
A210375 is also the number of 2 X 2 matrices with all terms in {0,1,...,n} and (sum of terms) = 3n - 3.
LINKS
Index entries for linear recurrences with constant coefficients, signature (4, -6, 4, -1).
FORMULA
From Colin Barker, Dec 07 2017: (Start)
G.f.: x*(1 + 12*x - 14*x^2 - 4*x^3 + 6*x^4) / (1 - x)^4.
a(n) = (-120 + 74*n + 15*n^2 + n^3) / 6 for n > 1.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n > 5.
(End)
MATHEMATICA
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Mar 20 2012
STATUS
approved