Compose the natural numbers with themselves, A(x) = B(B(x)) where B(x) = x/(1-x)^2 is the generating function for natural numbers.

A030267

Compose the natural numbers with themselves, A(x) = B(B(x)) where B(x) = x/(1-x)^2 is the generating function for natural numbers.

Terms

    a(0) =1a(1) =4a(2) =14a(3) =46a(4) =145a(5) =444a(6) =1331a(7) =3926a(8) =11434a(9) =32960a(10) =94211a(11) =267384a(12) =754309a(13) =2116936a(14) =5914310a(15) =16458034a(16) =45638101a(17) =126159156a(18) =347769719a(19) =956238170a(20) =2623278946a(21) =7181512964a(22) =19622668679a(23) =53522804976a(24) =145753273225a(25) =396323283724

External references