15607654857domain: NAppears in sequencesa(n) = 2*a(n-1) + 7*a(n-2).at n=17A083100a(n) = 2*a(n-1) + 7*a(n-2) for n>1, a(0)=1, a(1)=1.at n=18A084058a(0)=1, a(1)=9, a(n) = 18*a(n-1) - 49*a(n-2) for n > 1.at n=9A165224