A108358 A mod 2 triangle based on floor((n+2)/2).

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1

Offset

0,1

Comments

Row sums are A108355. Diagonal sums are A108356.

Links

Table of n, a(n) for n=0..104.

Formula

Number triangle T(n, k)=(sum{j=0..n-k, C(k, j)C(n-j, k)*floor((j+2)/2)} mod 2); Column k has g.f. x^k(1+x(mod(a(k+2), 4)))/(1-x^a(k)) where a(n)=-3cos(pi*n/2)/2-3sin(pi*n/2)/2+5/2=(1, 1, 4, 4, 1, 1, 4, 4, ...). T(n, k)=A108359(n, k) mod 2.

Example

Rows begin
1;
1,1;
1,1,1;
1,1,1,1;
1,1,0,1,1;
1,1,0,0,1,1;
1,1,1,0,1,1,1;
1,1,1,1,1,1,1,1;

Crossrefs

Sequence in context: A131217 A105567 A114213 * A267959 A144384 A144475

Adjacent sequences: A108355 A108356 A108357 * A108359 A108360 A108361

Keyword

easy,nonn,tabl

Author

Paul Barry, May 31 2005

Status

approved