G.f. is 1 - 1/f(x), where f(x) = 1+x+3*x^2+9*x^3+32*x^4+... is 1/x times g.f. for A063020.
A007858
G.f. is 1 - 1/f(x), where f(x) = 1+x+3*x^2+9*x^3+32*x^4+... is 1/x times g.f. for A063020.
Terms
- a(0) =1a(1) =2a(2) =4a(3) =13a(4) =44a(5) =164a(6) =636a(7) =2559a(8) =10556a(9) =44440a(10) =190112a(11) =824135a(12) =3612244a(13) =15981632a(14) =71277736a(15) =320121747a(16) =1446537564a(17) =6571858168a(18) =30000766128a(19) =137544893940a(20) =633051803120
External references
- oeis: A007858