Number of Twopins positions.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =15a(5) =28a(6) =51a(7) =92a(8) =165a(9) =294a(10) =522a(11) =924a(12) =1632a(13) =2878a(14) =5069a(15) =8920a(16) =15686a(17) =27570a(18) =48439a(19) =85080a(20) =149405a(21) =262320a(22) =460515a(23) =808380a(24) =1418916a(25) =2490432a(26) =4370944a(27) =7671188a(28) =13462945a(29) =23627078