Number of bipartite partitions of n white objects and 2 black ones.

Terms

a(0) =2a(1) =4a(2) =9a(3) =16a(4) =29a(5) =47a(6) =77a(7) =118a(8) =181a(9) =267a(10) =392a(11) =560a(12) =797a(13) =1111a(14) =1541a(15) =2106a(16) =2863a(17) =3846a(18) =5142a(19) =6808a(20) =8973a(21) =11733a(22) =15275a(23) =19753a(24) =25443a(25) =32582a(26) =41569a(27) =52770a(28) =66757a(29) =84078