Third diagonal of Catalan difference table (A059346).

Terms

a(0) =5a(1) =9a(2) =19a(3) =43a(4) =102a(5) =250a(6) =628a(7) =1608a(8) =4181a(9) =11009a(10) =29295a(11) =78655a(12) =212815a(13) =579675a(14) =1588245a(15) =4374285a(16) =12103407a(17) =33628827a(18) =93786969a(19) =262450881a(20) =736710360a(21) =2073834420a(22) =5853011850a(23) =16558618510a(24) =46949351275a(25) =133390812255a(26) =379708642289