OFFSET
0,2
COMMENTS
Diagonal sums of number triangle A117377.
LINKS
Index entries for linear recurrences with constant coefficients, signature (0, 1, -1).
FORMULA
a(n)=sum{k=0..floor(n/2), (-1)^n*(C(k,n-2k)+4*C(k, n-2k-1))}
MATHEMATICA
CoefficientList[Series[(1-4x)/(1-x^2+x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[ {0, 1, -1}, {1, -4, 1}, 40] (* Harvey P. Dale, Nov 08 2022 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Mar 10 2006
STATUS
approved