Numbers of Twopins positions.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =7a(5) =10a(6) =14a(7) =20a(8) =30a(9) =45a(10) =69a(11) =104a(12) =157a(13) =236a(14) =356a(15) =540a(16) =821a(17) =1252a(18) =1908a(19) =2909a(20) =4434a(21) =6762a(22) =10319a(23) =15755a(24) =24066a(25) =36766a(26) =56176a(27) =85837a(28) =131172a(29) =200471