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A305238 Negative numbers in base -10. 4
19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60, 79, 78, 77, 76, 75 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = A039723(-n).

Also base -10 representation of -n reinterpreted as decimal numbers.

The first comment is slightly misleading because sequence A039723 isn't defined for n < 0, and none of the terms a(n) here is a term of A039723. However, it can be seen as the definition of the extension of A039723 to negative indices. Also, the (naïve) recursive definition or implementation of A039723 requires that function to be defined for negative arguments, and using the generic formula it will work as expected for -n, n > 0. - M. F. Hasler, Oct 16 2018

LINKS

Jianing Song, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Negadecimal

Eric Weisstein's World of Mathematics, Negabinary

Wikipedia, Negative base

EXAMPLE

-1 in base -10 is represented as 19 (1*(-10) + 9 = -1), so a(1) = 19;

-11 in base -10 is represented as 29 (2*(-10) + 9 = -11), so a(11) = 29;

-99 in base -10 is represented as 1901 (1*(-10)^3 + 9*(-10)^2 + 1 = -99), so a(99) = 1901.

PROG

(PARI) A305238(n)=A039723(-n) \\ M. F. Hasler, Oct 16 2018

CROSSREFS

Cf. A039724 (nonnegative numbers in base -2), A212529 (negative numbers in base -2), A007608 (nonnegative numbers in base -4), A212526 (negative numbers in base -4), A039723 (nonnegative numbers in base -10).

Sequence in context: A230339 A022975 A023461 * A004460 A082126 A176411

Adjacent sequences:  A305235 A305236 A305237 * A305239 A305240 A305241

KEYWORD

nonn,base,easy

AUTHOR

Jianing Song, Jun 19 2018

STATUS

approved

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Last modified March 18 12:10 EDT 2019. Contains 321283 sequences. (Running on oeis4.)