A292598 a(n) is the number of odd primes in the sequence [n, floor(n/2), floor(n/4), ..., 1].

0, 0, 1, 0, 1, 1, 2, 0, 0, 1, 2, 1, 2, 2, 2, 0, 1, 0, 1, 1, 1, 2, 3, 1, 1, 2, 2, 2, 3, 2, 3, 0, 0, 1, 1, 0, 1, 1, 1, 1, 2, 1, 2, 2, 2, 3, 4, 1, 1, 1, 1, 2, 3, 2, 2, 2, 2, 3, 4, 2, 3, 3, 3, 0, 0, 0, 1, 1, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 2, 2, 3, 2, 2, 3, 3, 4, 4, 1, 2, 1, 1, 1, 2, 1, 2, 2, 2

Offset

1,7

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Formula

a(1) = a(2) = 0; for n > 2, a(n) = A010051(n) + a(floor(n/2)).

a(n) = A000120(A292596(n)).

For all n >= 1, a(n) <= A078349(n).

Prog

(Scheme, with memoization-macro definec)
(definec (A292598 n) (if (<= n 2) 0 (+ (A010051 n) (A292598 (floor->exact (/ n 2))))))

Crossrefs

Cf. A010051, A065091, A078349, A292596.

Sequence in context: A049321 A204425 A245187 * A079113 A144874 A333365

Adjacent sequences: A292595 A292596 A292597 * A292599 A292600 A292601

Keyword

nonn

Author

Antti Karttunen, Sep 27 2017

Status

approved