A187035 Diagonal sums of number triangle A187034.

1, 0, 1, -1, 1, -1, 2, -1, 2, -2, 2, -2, 3, -2, 3, -3, 3, -3, 4, -3, 4, -4, 4, -4, 5, -4, 5, -5, 5, -5, 6, -5, 6, -6, 6, -6, 7, -6, 7, -7, 7, -7, 8, -7, 8, -8, 8, -8, 9, -8, 9, -9, 9, -9, 10, -9, 10, -10, 10, -10, 11

Offset

0,7

Comments

Absolute values appear to be given (with the same offset) by A103221. - Jason Kimberley, Oct 17 2011

Links

Table of n, a(n) for n=0..60.

Index entries for linear recurrences with constant coefficients, signature (0,1,-1,0,1).

Formula

Conjectured: G.f. 1/( (1-x)*(1-x+x^2)*(1+x)^2 ) with a(n) = +a(n-2) -a(n-3) +a(n-5). - R. J. Mathar, Jun 30 2011

The above conjecture is correct. [Charles R Greathouse IV, Dec 28 2011]

Prog

(PARI) a(n)=(-1)^n*(n\2-(n-1)\3) \\ Charles R Greathouse IV, Dec 28 2011

Crossrefs

Sequence in context: A306468 A032358 A011960 * A008615 A103221 A026806

Adjacent sequences: A187032 A187033 A187034 * A187036 A187037 A187038

Keyword

sign,easy

Author

Paul Barry, Mar 08 2011

Status

approved