Central factorial numbers: A008955(n,2).

Terms

a(0) =4a(1) =49a(2) =273a(3) =1023a(4) =3003a(5) =7462a(6) =16422a(7) =32946a(8) =61446a(9) =108031a(10) =180895a(11) =290745a(12) =451269a(13) =679644a(14) =997084a(15) =1429428a(16) =2007768a(17) =2769117a(18) =3757117a(19) =5022787a(20) =6625311a(21) =8632866a(22) =11123490a(23) =14185990a(24) =17920890a(25) =22441419a(26) =27874539a(27) =34362013a(28) =42061513a(29) =51147768