A122587 Leading digit of n in base 4.

1, 2, 3, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1

Offset: 1

Author

Peter C. Heinig (algorithms(AT)gmx.de), Oct 20 2006

Keywords

• easy
• nonn
• base

Comments

Digits 1, 2 and 3 appear cyclically and each time in runs whose lengths are the powers of 4.

Examples

			a(1) = 1/(4^0) = 1.
		

Programs

Maple

seq( evalf(floor(n/ (4^floor(log[4](n))))), n=1..500);

Mathematica

Table[First[IntegerDigits[n, 4]], {n, 100}] (* Alonso del Arte, Sep 30 2011 *)

Python

def A122587(n): return int(bin(n)[2:3+(n.bit_length()&1^1)],2) # Chai Wah Wu, Jan 30 2023

Formula

a(n) = floor(n/(4^floor(log[4](n)))).