a(n) = Sum_{k=0..n} k^(2*k).A350008a(n) = Sum_{k=0..n} k^(2*k).Terms a(0) =1a(1) =2a(2) =18a(3) =747a(4) =66283a(5) =9831908a(6) =2186614244a(7) =680409687093External referencesoeis: A350008