A268643 Number of 1's in decimal representation of n.

0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1

Offset: 0

Author

Robert Israel, Feb 09 2016

Keywords

• nonn
• base

Links

• Robert Israel, Table of n, a(n) for n = 0..10000

Crossrefs

Second column of A100910.

Programs

Maple

f:= n -> numboccur(1,convert(n,base,10)):
map(f, [$0..100]);

Mathematica

DigitCount[Range[0,120],10,1] (* Harvey P. Dale, Apr 08 2018 *)

Python

def A268643(n): return str(n).count('1') # Chai Wah Wu, Dec 23 2022

Formula

a(n) = a(floor(n/10)) + 1 if n == 1 (mod 10), otherwise a(n) = a(floor(n/10)).

G.f. g(x) satisfies g(x) = x/(1-x^10) + (1-x^10)*g(x^10)/(1-x).