A274151 Number of integers in n-th generation of tree T(-3/4) defined in Comments.

1, 1, 1, 1, 1, 2, 2, 2, 2, 4, 5, 6, 8, 11, 14, 17, 20, 26, 36, 45, 56, 74, 96, 120, 150, 191, 245, 318, 405, 517, 665, 850, 1073, 1364, 1749, 2233, 2860, 3660, 4678, 5970, 7610, 9691, 12357, 15808, 20190, 25815, 32990, 42127, 53730, 68537, 87474, 111636, 142653, 182214, 232784, 297231, 379421

Offset

0,6

Comments

Let T* be the infinite tree with root 0 generated by these rules: if p is in T*, then p+1 is in T* and x*p is in T*. Let g(n) be the set of nodes in the n-th generation, so that g(0) = {0}, g(1) = {1}, g(2) = {2,x}, g(3) = {3,2x,x+1,x^2}, etc. Let T(r) be the tree obtained by substituting r for x.

See A274142 for a guide to related sequences.

Links

Kenny Lau, Table of n, a(n) for n = 0..9418

Example

For r = -3/4, we have g(3) = {3,2r,r+1, r^2}, in which the number of integers is a(3) = 1.

Mathematica

z = 18; t = Join[{{0}}, Expand[NestList[DeleteDuplicates[Flatten[Map[{# + 1, x*#} &, #], 1]] &, {1}, z]]];
u = Table[t[[k]] /. x -> -3/4, {k, 1, z}];
Table[Count[Map[IntegerQ, u[[k]]], True], {k, 1, z}]

Crossrefs

Cf. A274142.

Sequence in context: A286305 A046768 A363405 * A216393 A045812 A064877

Adjacent sequences: A274148 A274149 A274150 * A274152 A274153 A274154

Keyword

nonn,easy

Author

Clark Kimberling, Jun 11 2016

Extensions

More terms from Kenny Lau, Jul 02 2016

Status

approved