Number of numbers expressible as b(1)*b(2)*...*b(n) with 1 <= b(i) <= i for each i.

Terms

a(0) =1a(1) =2a(2) =5a(3) =11a(4) =30a(5) =64a(6) =178a(7) =382a(8) =758a(9) =1367a(10) =3620a(11) =7193a(12) =19707a(13) =40867a(14) =75706a(15) =130017a(16) =339506a(17) =667390a(18) =1824656a(19) =3724917a(20) =6785689a(21) =11545898a(22) =30099090a(23) =58833294a(24) =105348580a(25) =176098677a(26) =282847446a(27) =438090287a(28) =1095200628a(29) =2057512312