Number of non-isomorphic multiset partitions of weight n using singletons or pairs.

Terms

a(0) =1a(1) =1a(2) =4a(3) =7a(4) =21a(5) =40a(6) =106a(7) =216a(8) =534a(9) =1139a(10) =2715a(11) =5962a(12) =14012a(13) =31420a(14) =73484a(15) =167617a(16) =392714a(17) =908600a(18) =2140429a(19) =5015655a(20) =11905145a(21) =28228533a(22) =67590229a(23) =162067916a(24) =391695348a(25) =949359190a(26) =2316618809a(27) =5673557284a(28) =13979155798a(29) =34583650498