Numbers of polypentagons with one internal vertex (see Cyvin et al. for precise definition).

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =12a(5) =29a(6) =72a(7) =170a(8) =404a(9) =944a(10) =2184a(11) =5000a(12) =11368a(13) =25616a(14) =57376a(15) =127696a(16) =282688a(17) =622656a(18) =1365472a(19) =2982016a(20) =6488320a(21) =14068672a(22) =30409216a(23) =65536512a(24) =140859776a(25) =301990912a(26) =645924864a(27) =1378530048