a(n) = a(n-1)*3^n + 1 where a(0)=1.A371441a(n) = a(n-1)*3^n + 1 where a(0)=1.Terms a(0) =1a(1) =4a(2) =37a(3) =1000a(4) =81001a(5) =19683244a(6) =14349084877External referencesoeis: A371441