a(n) = Sum_{j=0..15} n^j.A105312a(n) = Sum_{j=0..15} n^j.Terms a(0) =1a(1) =16a(2) =65535a(3) =21523360a(4) =1431655765a(5) =38146972656a(6) =564221981491External referencesoeis: A105312