A292772 a(n) = cardinality of a certain set of natural numbers defined using A117818.

1, 2, 3, 4, 6, 8, 12, 18, 25, 38, 56, 89, 138, 218, 342, 547, 882, 1429, 2299, 3705, 5961, 9615, 15524, 25057, 40442, 65247, 105412, 170224, 274963, 44156, 717551, 1159406, 1873356

Offset

0,2

Comments

Let s(n) = A117818(n). Define sets C_n of natural numbers by C_0 = {1}; C_(n+1) = C_n union {s(x+y): x, y in C_n} for n >= 0. Then a(n) = |C_n|.

Links

Table of n, a(n) for n=0..32.

Mihai Caragiu, P. A. Vicol, and M. Kaki, On Conway's subprime function, a covering of N and an unexpected appearance of the golden ratio, Fib. Q., 55 (2017), no. 4, 327-331.

Crossrefs

Cf. A117818.

Sequence in context: A319054 A074964 A017822 * A179042 A222786 A353405

Adjacent sequences: A292769 A292770 A292771 * A292773 A292774 A292775

Keyword

nonn,more

Author

N. J. A. Sloane, Sep 29 2017

Status

approved