a(n) = A215082(2*n).

Terms

a(0) =0a(1) =1a(2) =4a(3) =8a(4) =17a(5) =35a(6) =66a(7) =124a(8) =229a(9) =414a(10) =742a(11) =1318a(12) =2320a(13) =4059a(14) =7062a(15) =12224a(16) =21071a(17) =36185a(18) =61930a(19) =105678a(20) =179847a(21) =305326a(22) =517212a(23) =874380a(24) =1475472a(25) =2485573a(26) =4180648a(27) =7021544a(28) =11777117a(29) =19728911