OFFSET
0,2
COMMENTS
Equals row sums of triangle A179743.
LINKS
FORMULA
a(0) = 1, a(1) = 2; a(n) = 2*a(n-1) + (n-2) for n>1.
G.f. 1-x*(2-4*x+3*x^2) / ( (2*x-1)*(x-1)^2 ). - R. J. Mathar, May 03 2013
EXAMPLE
a(5) = 43 = 2*a(4) + 3 = 2*20 + 3
a(5) = 43 = sum of row 5 terms, triangle A179743: (1 + 5 + 8 + 12 + 16 + 1).
MATHEMATICA
a[0] = 1; a[1] = 2; a[n_] := a[n] = 2 a[n - 1] + (n - 2); Array[a, 35, 0] (* Robert G. Wilson v, Aug 03 2010 *)
PROG
(PARI) a(n)=3*2^n\2-n \\ Charles R Greathouse IV, May 03 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson, Jul 25 2010
EXTENSIONS
More terms from Robert G. Wilson v, Aug 03 2010
STATUS
approved