Half-convolution of Catalan sequence A000108 with itself.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =23a(5) =66a(6) =227a(7) =715a(8) =2529a(9) =8398a(10) =30275a(11) =104006a(12) =380162a(13) =1337220a(14) =4939443a(15) =17678835a(16) =65844845a(17) =238819350a(18) =895451117a(19) =3282060210a(20) =12374186318a(21) =45741281820a(22) =173257703723a(23) =644952073662