546876domain: NAppears in sequencesa(n) = n*5^n + 1.at n=7A050916Number 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=8A154089a(n) = 7*5^n+1.at n=7A199310