From higher-order Bernoulli numbers: denominator of D Number D2n(2n).

Terms

a(0) =1a(1) =3a(2) =15a(3) =21a(4) =45a(5) =33a(6) =1365a(7) =45a(8) =765a(9) =1995a(10) =3465a(11) =1035a(12) =20475a(13) =189a(14) =435a(15) =7161a(16) =58905a(17) =315a(18) =959595a(19) =4095a(20) =142065a(21) =148995a(22) =108675a(23) =14805a(24) =2436525a(25) =65637a(26) =78705a(27) =21945a(28) =24795a(29) =2655