Number of Twopins positions.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =7a(5) =10a(6) =13a(7) =18a(8) =24a(9) =35a(10) =50a(11) =75a(12) =109a(13) =161a(14) =231a(15) =336a(16) =482a(17) =703a(18) =1020a(19) =1498a(20) =2188a(21) =3214a(22) =4694a(23) =6877a(24) =10039a(25) =14699a(26) =21487a(27) =31489a(28) =46097a(29) =67582