OFFSET
0,2
COMMENTS
Northwest diagonal sums of A134658, omitting row 0.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,-1,1).
FORMULA
O.g.f.: -1/(x+1)-2/(x-1)+x/(x^2-x+1). a(n) = 2-(-1)^n+A010892(n-1). - R. J. Mathar, Feb 08 2008
From Wesley Ivan Hurt, Jun 18 2016: (Start)
a(n) = a(n-1) - a(n-3) + a(n-4) for n>3.
a(n) = (6-3*cos(n*Pi)+2*sqrt(3)*sin(n*Pi/3))/3. (End)
MAPLE
A134977:=n->[1, 4, 2, 3, 0, 2][(n mod 6)+1]: seq(A134977(n), n=0..100); # Wesley Ivan Hurt, Jun 18 2016
MATHEMATICA
Flatten[Table[{1, 4, 2, 3, 0, 2}, {20}]] (* Wesley Ivan Hurt, Jun 18 2016 *)
PadRight[{}, 100, {1, 4, 2, 3, 0, 2}] (* Vincenzo Librandi, Jun 19 2016 *)
PROG
(Magma) &cat[[1, 4, 2, 3, 0, 2]^^20]; // Wesley Ivan Hurt, Jun 18 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Feb 04 2008
STATUS
approved