A111527 Inverse of A111526. Row sums have general term C(n,floor(n/2))*(cos(Pi*n/2) + sin(Pi*n/2)).

1, 0, 1, -3, 0, 1, 0, -4, 0, 1, 10, 0, -5, 0, 1, 0, 15, 0, -6, 0, 1, -35, 0, 21, 0, -7, 0, 1, 0, -56, 0, 28, 0, -8, 0, 1, 126, 0, -84, 0, 36, 0, -9, 0, 1, 0, 210, 0, -120, 0, 45, 0, -10, 0, 1, -462, 0, 330, 0, -165, 0, 55, 0, -11, 0, 1, 0, -792, 0, 495, 0, -220, 0, 66, 0, -12, 0, 1, 1716, 0, -1287, 0, 715, 0, -286, 0, 78, 0, -13, 0, 1

Offset: 0

Author

Paul Barry, Aug 05 2005

Keywords

• easy
• sign
• tabl

Comments

Inverse of a scaled Chebyshev triangle.

Examples

			Triangle begins
    1;
    0,  1;
   -3,  0,  1;
    0, -4,  0,  1;
   10,  0, -5,  0,  1;
    0, 15,  0, -6,  0,  1;
  -35,  0, 21,  0, -7,  0,  1;
		

Formula

Riordan array (c^2(-x^2)(1+x^2c(-x^2))/sqrt(1+4x^2), x*c(-x^2)), c(x) the g.f. of A000108.