Number of compositions of n into 2*j-1 kinds of j's for all j>=1.

Terms

a(0) =1a(1) =1a(2) =4a(3) =12a(4) =36a(5) =108a(6) =324a(7) =972a(8) =2916a(9) =8748a(10) =26244a(11) =78732a(12) =236196a(13) =708588a(14) =2125764a(15) =6377292a(16) =19131876a(17) =57395628a(18) =172186884a(19) =516560652a(20) =1549681956a(21) =4649045868a(22) =13947137604a(23) =41841412812a(24) =125524238436a(25) =376572715308