A351870 a(n) is the least k such that A351868(k) = n.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11111111111, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 112, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 1113, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 224, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 111115, 56, 57, 58, 59, 60, 61, 62

Offset

0,3

Links

Table of n, a(n) for n=0..62.

Rémy Sigrist, PARI program

Formula

a(n) <= A002275(n).

Example

For n = 44:
- the number 44 could encode 1 or 2 runs of consecutive equal digits,
- for 1 run, we have the following possibilities:
       11111111111111111111111111111111111111111111 (44 1's)
       2222222222222222222222 (22 2's)
       44444444444 (11 4's)
- for 2 runs, we have the following possibilities:
       11114 (4 1's and then 1 4's)
       224 (2 2's and then 1 4's)
       111122 (4 1's and then 2 2's)
       422 (1 4's and then 2 2's)
       221111 (2 2's and then 4 1's)
       41111 (1 4's and then 4 1's)
- the least possibility is 224,
- so a(44) = 224.

Prog

(PARI) See Links section.

Crossrefs

Cf. A002275, A351868.

Sequence in context: A004916 A120126 A062399 * A121603 A261333 A330430

Adjacent sequences: A351867 A351868 A351869 * A351871 A351872 A351873

Keyword

nonn,base

Author

Rémy Sigrist, Feb 22 2022

Status

approved