Number of integer compositions of n with exactly one part above the diagonal.

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =5a(5) =9a(6) =18a(7) =35a(8) =67a(9) =131a(10) =257a(11) =505a(12) =996a(13) =1973a(14) =3915a(15) =7781a(16) =15486a(17) =30855a(18) =61527a(19) =122764a(20) =245069a(21) =489412a(22) =977673a(23) =1953515a(24) =3904108a(25) =7803545a(26) =15599618a(27) =31187269a(28) =62355347a(29) =124679883