a(n) = Product_{k=1..n} (3*k^2+1).A277353a(n) = Product_{k=1..n} (3*k^2+1).Terms a(0) =1a(1) =4a(2) =52a(3) =1456a(4) =71344a(5) =5422144a(6) =591013696a(7) =87470027008External referencesoeis: A277353