Third convolution of A001405 (central binomial numbers).

Terms

a(0) =1a(1) =4a(2) =14a(3) =40a(4) =109a(5) =276a(6) =682a(7) =1624a(8) =3810a(9) =8744a(10) =19868a(11) =44496a(12) =98941a(13) =217780a(14) =476786a(15) =1036024a(16) =2241814a(17) =4823160a(18) =10342180a(19) =22076080a(20) =46994386a(21) =99673224a(22) =210923364a(23) =445000560a(24) =937051684a(25) =1968204496a(26) =4127285688a(27) =8636324768a(28) =18045851165a(29) =37638105588