Partial sums of A006343.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =7a(5) =17a(6) =51a(7) =163a(8) =561a(9) =2004a(10) =7391a(11) =27873a(12) =107050a(13) =417152a(14) =1645339a(15) =6555752a(16) =26348334a(17) =106691779a(18) =434851380a(19) =1782551286a(20) =7344326285a(21) =30397197514a(22) =126324028956a(23) =526911437207