OFFSET
0,3
COMMENTS
Diagonal sums of number triangle A115713.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (-1,-1,0,1,1,1)
FORMULA
G.f.: (1 - 3*x^2 + 4*x^3 + 3*x^4 + 4*x^5)/(1 + x + x^2 - x^4 - x^5 - x^6).
a(n) = Sum_{k=0..floor(n/2)} A115713(n-k, k).
MATHEMATICA
LinearRecurrence[{-1, -1, 0, 1, 1, 1}, {1, -1, -3, 0, 1, -5}, 80] (* G. C. Greubel, Nov 23 2021 *)
PROG
(Sage)
def A115714_list(prec):
P.<x> = PowerSeriesRing(ZZ, prec)
return P( (1-3*x^2+4*x^3+3*x^4+4*x^5)/(1+x+x^2-x^4-x^5-x^6) ).list()
A115714_list(80) # G. C. Greubel, Nov 23 2021
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Jan 29 2006
STATUS
approved