a(n) = T(2,n), array T given by A048505.

Terms

a(0) =1a(1) =10a(2) =35a(3) =101a(4) =269a(5) =685a(6) =1693a(7) =4093a(8) =9725a(9) =22781a(10) =52733a(11) =120829a(12) =274429a(13) =618493a(14) =1384445a(15) =3080189a(16) =6815741a(17) =15007741a(18) =32899069a(19) =71827453a(20) =156237821a(21) =338690045a(22) =731906045a(23) =1577058301a(24) =3388997629a(25) =7264534525a(26) =15535702013a(27) =33151778813a(28) =70598524925a(29) =150055419901