Number of multigraphs with loops on 3 nodes with n edges.

Terms

a(0) =1a(1) =2a(2) =6a(3) =14a(4) =28a(5) =52a(6) =93a(7) =152a(8) =242a(9) =370a(10) =546a(11) =784a(12) =1103a(13) =1512a(14) =2040a(15) =2706a(16) =3534a(17) =4554a(18) =5803a(19) =7304a(20) =9108a(21) =11252a(22) =13780a(23) =16744a(24) =20205a(25) =24206a(26) =28826a(27) =34126a(28) =40176a(29) =47056