651511domain: NAppears in sequencesa(n) = (9n^4 - 18n^3 + 18n^2 - 9n + 2)/2.at n=19A079903Triangular numbers obtained as a concatenation of successive terms of A081847.at n=7A082235Numerator of (9*(n^4 - 2*n^3 + 2*n^2 - n) + 2)/(2*(2*n-1)).at n=19A096430Triangular numbers composed of digits {1,5,6}.at n=15A119132