Central elements in 4-Pascal triangle A028275 (by row).

Terms

a(0) =1a(1) =4a(2) =10a(3) =32a(4) =110a(5) =392a(6) =1428a(7) =5280a(8) =19734a(9) =74360a(10) =281996a(11) =1074944a(12) =4115020a(13) =15808912a(14) =60917800a(15) =235350720a(16) =911315430a(17) =3535767000a(18) =13742347740a(19) =53495534400a(20) =208537056420a(21) =813950932080