67580

Appears in sequences

• Number of planar n X n X n binary triangular grids symmetric under 120 degree rotation with no more than 4 ones in any 5 X 5 X 5 subtriangle.at n=12A153935
• a(n) = 169*n^2 - n.at n=19A157998
• a(n) = 676*n^2 - 2*n.at n=9A158392
• a(n) = 400*n^2 - 20.at n=12A158597
• G.f. satisfies: A(x) = 1 + x*A(x)*A(-x) + x^2*A(x)/A(-x).at n=19A209199