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A320636 Negative numbers in base -3. 1
12, 11, 10, 22, 21, 20, 1202, 1201, 1200, 1212, 1211, 1210, 1222, 1221, 1220, 1102, 1101, 1100, 1112, 1111, 1110, 1122, 1121, 1120, 1002, 1001, 1000, 1012, 1011, 1010, 1022, 1021, 1020, 2202, 2201, 2200, 2212, 2211, 2210, 2222, 2221, 2220, 2102, 2101, 2100, 2112 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Extend A073785 to negative-indexed terms, then a(n) = A073785(-n).

LINKS

Table of n, a(n) for n=1..46.

Eric Weisstein's World of Mathematics, Negadecimal

Eric Weisstein's World of Mathematics, Negabinary

Wikipedia, Negative base

EXAMPLE

-7 in base -3 is represented as 1202 (1*(-3)^3 + 2*(-3)^2 + 2 = -7), so a(7) = 1202;

-16 in base -3 is represented as 1102 (1*(-3)^3 + 1*(-3)^2 + 2 = -16), so a(16) = 1102;

-40 in base -3 is represented as 2222 (2*(-3)^3 + 2*(-3)^2 + 2*(-3) + 2 = -99), so a(40) = 2222.

PROG

(PARI) A073785 = base(n, b=-3) = if(n, base(n\b, b)*10 + n%b, 0)

a(n) = A073785(-n)

CROSSREFS

Nonnegative numbers in negative bases: A039723 (b=-10), A039724 (b=-2), A073785 (b=-3), A007608 (b=-4), A073786 (b=-5), A073787 (b=-6), A073788 (b=-7), A073789 (b=-8), A073790 (b=-9).

Negative numbers in negative bases: A305238 (b=-10), A212529 (b=-2), this sequence (b=-3), A212526 (b=-4).

Sequence in context: A022968 A023454 A055123 * A070560 A019330 A086045

Adjacent sequences:  A320633 A320634 A320635 * A320637 A320638 A320639

KEYWORD

nonn,base

AUTHOR

Jianing Song, Oct 18 2018

STATUS

approved

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Last modified September 22 17:39 EDT 2021. Contains 347607 sequences. (Running on oeis4.)