a(n) = Sum_{k=0..m} (k+1) * A026009(n, m-k) where m = floor(n/2)+1.

Terms

a(0) =1a(1) =3a(2) =8a(3) =12a(4) =31a(5) =48a(6) =121a(7) =192a(8) =475a(9) =768a(10) =1872a(11) =3072a(12) =7398a(13) =12288a(14) =29295a(15) =49152a(16) =116179a(17) =196608a(18) =461284a(19) =786432a(20) =1833202a(21) =3145728a(22) =7290818a(23) =12582912a(24) =29014046a(25) =50331648a(26) =115521296a(27) =201326592a(28) =460153644a(29) =805306368