a(n) = (2*n+1)!*(2*n+3)/3.A165457a(n) = (2*n+1)!*(2*n+3)/3.Terms a(0) =1a(1) =10a(2) =280a(3) =15120a(4) =1330560a(5) =172972800a(6) =31135104000External referencesoeis: A165457