Denominator of Laguerre(n, -2).

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =1a(5) =15a(6) =45a(7) =105a(8) =315a(9) =405a(10) =4725a(11) =155925a(12) =467775a(13) =96525a(14) =42567525a(15) =638512875a(16) =30405375a(17) =10854718875a(18) =97692469875a(19) =618718975875a(20) =189403768125