a(n) = T(n,[ n/2 ]), where T is the array in A026374.

Terms

a(0) =1a(1) =3a(2) =4a(3) =11a(4) =17a(5) =45a(6) =75a(7) =195a(8) =339a(9) =873a(10) =1558a(11) =3989a(12) =7247a(13) =18483a(14) =34016a(15) =86515a(16) =160795a(17) =408105a(18) =764388a(19) =1936881a(20) =3650571a(21) =9238023a(22) =17501619a(23) =44241261a(24) =84179877a(25) =212601015a(26) =406020930a(27) =1024642875a(28) =1963073865a(29) =4950790605