Second differences of A000219.

Terms

a(0) =2a(1) =1a(2) =4a(3) =4a(4) =13a(5) =14a(6) =36a(7) =48a(8) =96a(9) =141a(10) =261a(11) =386a(12) =676a(13) =1030a(14) =1706a(15) =2619a(16) =4230a(17) =6462a(18) =10219a(19) =15568a(20) =24165a(21) =36627a(22) =56103a(23) =84428a(24) =127873a(25) =191201a(26) =286663a(27) =425802a(28) =632973a(29) =933995