515649domain: NAppears in sequencesNumber of planar triangular n X n X n nonnegative integer grids with mirror symmetry about one altitude with every similarly oriented 5 X 5 X 5 subtriangle summing to 13.at n=4A154089Numbers X such that X^2 + Y^2 = 3^(2*k) + 1 and X > Y > 0 and k is the ternary digit length of X-1.at n=36A369768