a(n) = 3^n*A003046(n+1)/A002457(n).A185149a(n) = 3^n*A003046(n+1)/A002457(n).Terms a(0) =1a(1) =1a(2) =3a(3) =27a(4) =756a(5) =68040a(6) =20207880a(7) =20228087880External referencesoeis: A185149