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

1,2

Comments

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

Links

Table of n, a(n) for n=1..105.

Formula

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

Example

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

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 *)

Prog

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

Crossrefs

Sequence in context: A337201 A327462 A255824 * A276333 A347380 A308638

Adjacent sequences: A122584 A122585 A122586 * A122588 A122589 A122590

Keyword

easy,nonn,base

Author

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

Status

approved