a(n) = T(n,0) + T(n,1) + ... + T(n,[ n/2 ]), T given by A026703.

Terms

a(0) =1a(1) =1a(2) =4a(3) =6a(4) =20a(5) =32a(6) =101a(7) =165a(8) =507a(9) =837a(10) =2531a(11) =4205a(12) =12583a(13) =20993a(14) =62368a(15) =104354a(16) =308438a(17) =517146a(18) =1522818a(19) =2557110a(20) =7508968a(21) =12623188a(22) =36990948a(23) =62237324a(24) =182092022a(25) =306566670a(26) =895859156a(27) =1508992496a(28) =4405521688a(29) =7423506680