A392339 Number of decimal digit 1's in A006937(n).

1, 2, 7, 14, 44, 158, 535, 1821, 6092, 20000, 66378, 220957, 733556, 2436430, 8095687, 26892148, 89338832, 296769545, 985760656, 3274702309, 10878267642, 36136741115

Offset

1,2

Links

Table of n, a(n) for n=1..22.

Formula

a(n) = A000120(A008559(n)). - Alois P. Heinz, Jan 07 2026

Example

For n=2: A006937(2) = 1010 thus a(2) = 2.
For n=3: A006937(3) = 1111110010 thus a(3) = 7.

Maple

b:= proc(n) option remember;
      `if`(n=1, 2, convert(b(n-1), binary))
    end:
a:= proc(n) option remember; add(i, i=Bits[Split](b(n))) end:
seq(a(n), n=1..12);  # Alois P. Heinz, Jan 07 2026

Prog

(Python)
from itertools import islice
from gmpy2 import digits, mpz, popcount
def agen(): # generator of terms
    an = 2
    while True:
        yield popcount(an)
        an = mpz(digits(an, 2))
print(list(islice(agen(), 16))) # Michael S. Branicky, Jan 07 2026

Crossrefs

Cf. A000120, A006937, A008559, A242347.

Sequence in context: A018526 A329115 A018542 * A018577 A121118 A128882

Adjacent sequences: A392336 A392337 A392338 * A392340 A392341 A392342

Keyword

nonn,base,hard,more

Author

Lucas Griego, Jan 07 2026

Extensions

a(13)-a(15) from Alois P. Heinz, Jan 07 2026

a(16)-a(22) from Michael S. Branicky, Jan 08 2026

Status

approved