A212556 Representations of nonnegative integers in base -4: The range of A007608.

0, 1, 2, 3, 100, 101, 102, 103, 110, 111, 112, 113, 120, 121, 122, 123, 130, 131, 132, 133, 200, 201, 202, 203, 210, 211, 212, 213, 220, 221, 222, 223, 230, 231, 232, 233, 300, 301, 302, 303, 310, 311, 312, 313, 320, 321, 322, 323, 330, 331, 332, 333, 10000

Offset: 1

Author

M. F. Hasler, May 20 2012

Keywords

• nonn
• base

Comments

Also: Numbers with an odd number of digits, using only digits 0 through 3.

(These numbers (or strings of digits) represent nonnegative integers in base -4, while the same type of numbers with an even number of digits represent negative numbers. See references in A007608 for more information.)

Crossrefs

The same as A007608 sorted in increasing order.

Programs

PARI

{forstep(d=1,3,2, my(u=vector(d,i,10^(d-i))~); forvec(v=vector(d,i,[i==1 & d>1,3]),print1(v*u",")))}

PARI

is_A212556(n)==(#n=Str(n))%2 & !setminus(Set(Vec(n)),Vec("0123"))