a(n) = (10^n)^2 + 7*(10^n) + 1.A225813a(n) = (10^n)^2 + 7*(10^n) + 1.Terms a(0) =9a(1) =171a(2) =10701a(3) =1007001a(4) =100070001a(5) =10000700001External referencesoeis: A225813