OFFSET
1,5
COMMENTS
Also the NW-SE diagonal sums of A173402.
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,0,-2,2,0,-1).
FORMULA
a(n)= 2*a(n-1) -2*a(n-3) +2*a(n-4) -a(n-6). - R. J. Mathar, Mar 01 2010
G.f.: x^4 / ( (x-1)*(1+x)*(x^2-x+1)*(x^2+x-1) ). - R. J. Mathar, Nov 03 2016
MATHEMATICA
CoefficientList[Series[x^4/((x-1)(1+x)(x^2-x+1)(x^2+x-1)), {x, 0, 40}], x] (* or *) LinearRecurrence[{2, 0, -2, 2, 0, -1}, {0, 0, 0, 0, 1, 2}, 40] (* Harvey P. Dale, Jun 29 2021 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mark Dols, Feb 18 2010
STATUS
approved