a(n) = T(n,0) + T(n,1) + ... + T(n,[ n/2 ]), T given by A026714.

Terms

a(0) =1a(1) =1a(2) =4a(3) =6a(4) =21a(5) =34a(6) =113a(7) =188a(8) =607a(9) =1023a(10) =3246a(11) =5509a(12) =17290a(13) =29465a(14) =91820a(15) =156878a(16) =486549a(17) =832671a(18) =2574116a(19) =4410189a(20) =13602994a(21) =23323442a(22) =71826377a(23) =123216902a(24) =379031585a(25) =650462028a(26) =1999308247a(27) =3431941721a(28) =10542607578a(29) =18100449404