Number of compositions of n into 3*j-1 kinds of j's for all j >= 1.

Terms

a(0) =1a(1) =2a(2) =9a(3) =36a(4) =144a(5) =576a(6) =2304a(7) =9216a(8) =36864a(9) =147456a(10) =589824a(11) =2359296a(12) =9437184a(13) =37748736a(14) =150994944a(15) =603979776a(16) =2415919104a(17) =9663676416a(18) =38654705664a(19) =154618822656a(20) =618475290624