a(n) = (37^n - 1)/36.A218740a(n) = (37^n - 1)/36.Terms a(0) =0a(1) =1a(2) =38a(3) =1407a(4) =52060a(5) =1926221a(6) =71270178a(7) =2636996587a(8) =97568873720External referencesoeis: A218740