Number of Twopins positions.

Terms

a(0) =1a(1) =2a(2) =4a(3) =6a(4) =11a(5) =18a(6) =32a(7) =52a(8) =88a(9) =142a(10) =236a(11) =382a(12) =629a(13) =1018a(14) =1664a(15) =2692a(16) =4383a(17) =7092a(18) =11520a(19) =18640a(20) =30232a(21) =48916a(22) =79264a(23) =128252a(24) =207705a(25) =336074a(26) =544084