Number of 6-indecomposable (connected) graphs on n nodes.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =6a(5) =21a(6) =112a(7) =853a(8) =11117a(9) =261080a(10) =11716571a(11) =1006700565a(12) =164159a(13) =422662a(14) =1295037a(15) =4272969a(16) =12780650a(17) =23303620a(18) =64379033a(19) =189490870a(20) =556338383a(21) =1448500351a(22) =2871171041a(23) =7624849834a(24) =20914847051a(25) =55714746424a(26) =133364472272a(27) =277569288280a(28) =708402263349