A117379 Expansion of (1-4x)/(1-x^2+x^3).

1, -4, 1, -5, 5, -6, 10, -11, 16, -21, 27, -37, 48, -64, 85, -112, 149, -197, 261, -346, 458, -607, 804, -1065, 1411, -1869, 2476, -3280, 4345, -5756, 7625, -10101, 13381, -17726, 23482, -31107, 41208

Offset

0,2

Comments

Diagonal sums of number triangle A117377.

Links

Table of n, a(n) for n=0..36.

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

Sequence in context: A099310 A021880 A075013 * A007309 A352186 A333341

Adjacent sequences: A117376 A117377 A117378 * A117380 A117381 A117382

Keyword

easy,sign

Author

Paul Barry, Mar 10 2006

Status

approved