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A344486 a(n) is the least k such that the sum of digits of k is a substring of n and the sum of digits of n is a substring of k. 2
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 29, 39, 49, 59, 69, 79, 89, 99, 10, 2, 399, 499, 599, 699, 799, 899, 999, 101, 11, 3, 4999, 5999, 6999, 7999, 8999, 9999, 102, 111, 12, 4, 59999, 69999, 79999, 89999, 99999, 103, 112, 112, 13, 5, 699999, 799999, 899999, 999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

The sequence is well defined:

- for any number n with sum of digits d,

- by necessity, d <= n,

- the number k obtained by concatenating n-d 1's in front of d meets the requirements.

LINKS

Table of n, a(n) for n=0..54.

Rémy Sigrist, Perl program for A344486

FORMULA

a(10 * n) = a(n).

EXAMPLE

For n = 11:

- the sum of digits of 11 is 2,

- the sum of digits of a(n) must equal 1 or 11,

    - the numbers whose sum of digits is 1 are the powers of 10,

    - 2 cannot be a substring of a power of 10,

    - the first number with sum of digits 11 is 29,

    - 2 is a substring of 29,

- so a(11) = 29.

PROG

(Perl) See Links section.

CROSSREFS

Cf. A007953, A052018, A344487.

Sequence in context: A121760 A061816 A083960 * A138795 A297233 A177895

Adjacent sequences:  A344483 A344484 A344485 * A344487 A344488 A344489

KEYWORD

nonn,base

AUTHOR

Rémy Sigrist, May 21 2021

STATUS

approved

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Last modified September 22 22:38 EDT 2021. Contains 347609 sequences. (Running on oeis4.)