Sequence relating to the 11-gon (or hendecagon).

Terms

a(0) =0a(1) =1a(2) =4a(3) =14a(4) =50a(5) =175a(6) =616a(7) =2163a(8) =7601a(9) =26703a(10) =93819a(11) =329615a(12) =1158052a(13) =4068623a(14) =14294449a(15) =50221212a(16) =176444054a(17) =619907431a(18) =2177943781a(19) =7651850657a(20) =26883530748a(21) =94450905714a(22) =331837870408