a(n) is the number of simple graphs of order n having at most one cycle (such graphs are called "at most unicyclic graphs").
A291648
a(n) is the number of simple graphs of order n having at most one cycle (such graphs are called "at most unicyclic graphs").
Terms
- a(0) =1a(1) =2a(2) =4a(3) =9a(4) =19a(5) =45a(6) =105a(7) =261a(8) =657a(9) =1708a(10) =4498a(11) =12081a(12) =32752a(13) =89792a(14) =247893a(15) =689004a(16) =1924357a(17) =5398587a(18) =15197830a(19) =42917215a(20) =121507597a(21) =344806293a(22) =980423528a(23) =2792741331a(24) =7967842859a(25) =22765631866a(26) =65131178683a(27) =186560990191a(28) =53497417058
External references
- oeis: A291648