A235202 Numbers written in an alternating binary-then-quaternary base.

1, 10, 11, 20, 21, 30, 31, 100, 101, 110, 111, 120, 121, 130, 131, 1000, 1001, 1010, 1011, 1020, 1021, 1030, 1031, 1100, 1101, 1110, 1111, 1120, 1121, 1130, 1131, 2000, 2001, 2010, 2011, 2020, 2021, 2030, 2031, 2100

Offset

1,2

Comments

Mixed-radix number representation produced by a serial counter with generating sequence (1, 3, 1, 3, ...) = A010684.

Places reading from the right have values (1, 2, 8, 16, 64, 128, ...) = unsigned A094014.

Conjecture: This sequence interpreted as quaternary (base 4) numbers gives A126001 (hence a simplified scheme for computing that sequence).

Links

Jeremy Gardiner, Table of n, a(n) for n = 1..1024

Example

a(15) = 131 since 15 = 1*1+3*2+1*8.

Prog

(Chipmunk BASIC) # see www.nicholson.com/rhn/basic/
do : rem serial counter
z=z+1
if z>1 then z=0 : y=y+1
if y>3 then y=0 : x=x+1
if x>1 then x=0 : w=w+1
if w>3 then print : end
s$=str$(w)+str$(x)+str$(y)+str$(z)
c=val(s$) : rem strip leading zeros
print str$(c)+", ";
loop

Crossrefs

Cf. A109827 (Numbers written in an alternating binary-then-ternary base).

Sequence in context: A197652 A261909 A325483 * A049345 A007623 A109827

Adjacent sequences: A235199 A235200 A235201 * A235203 A235204 A235205

Keyword

nonn,base

Author

Jeremy Gardiner, Jan 04 2014

Status

approved