Erroneous version of A188900.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =8a(5) =16a(6) =31a(7) =60a(8) =114a(9) =215a(10) =402a(11) =7464a(12) =1375a(13) =2520a(14) =4593a(15) =8329a(16) =15036a(17) =27027a(18) =48389a(19) =86314a(20) =153432