4966055936domain: NAppears in sequencesa(n) is the number of occurrences of 7's in the palindromic compositions of 2*n-1, or also, the number of occurrences of 8's in the palindromic compositions of 2*n.at n=27A079861Expansion of (1+8x^2+8x^3)/((1-2x)^2*(1+2x+4x^2)).at n=27A168057