OFFSET
1,2
FORMULA
Binomial transform of [1, 4, 10, 20, 0, 0, 0, ...], where (1, 4, 10, 20) = row 3 of triangle A046899
a(n) = (-39 + 77*n - 45*n^2 + 10*n^3)/3. - T. D. Noe, Aug 22 2008
G.f.: x*(1+x+5*x^2+13*x^3)/(1-x)^4. - Colin Barker, Mar 23 2012
EXAMPLE
a(4) = 63 = (1, 3, 3, 1) dot (1, 4, 10, 20) = (1 + 12 + 30 + 20).
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson, Jul 27 2008
EXTENSIONS
More terms from T. D. Noe, Aug 22 2008
STATUS
approved