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User: Adil Soubki

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A373701 Extension of Mahler-Popken complexity to the rationals. The minimal number of 1's required to build the n-th positive rational in the Cantor ordering using only +, /, and *.

Original entry on oeis.org

1, 3, 2, 4, 3, 5, 5, 4, 4, 6, 5, 6, 7, 7, 5, 5, 5, 7, 8, 6, 6, 7, 8, 9, 6, 6, 6, 7, 9, 6, 6, 8, 8, 9, 10, 7, 7, 8, 7, 7, 7, 9, 11, 8, 8, 8, 10, 10, 10, 10, 11, 7, 9, 7, 7, 8, 7, 9, 11, 11, 10, 8, 8, 9, 10, 12, 12, 8, 9, 8, 8, 9, 11, 13, 12, 9, 8, 8, 8, 9, 10
Offset: 1

Author

Adil Soubki, Jun 13 2024

Keywords

Comments

Since we do not require that rationals with denominator 1 be written in the form p/q (i.e., we allow them to be written as p), this reduces to A005245 in the case where q = 1.

Examples

			|    | rational   |  minimal expression         |    a(n) |
|---:|:-----------|:----------------------------|--------:|
|  1 | 1/1        | 1                           |       1 |
|  2 | 1/2        | 1/(1+1)                     |       3 |
|  3 | 2/1        | 1+1                         |       2 |
|  4 | 1/3        | 1/(1+1+1)                   |       4 |
|  5 | 3/1        | 1+1+1                       |       3 |
|  6 | 1/4        | 1/(1+1+1+1)                 |       5 |
|  7 | 2/3        | (1+1)/(1+1+1)               |       5 |
|  8 | 3/2        | 1+(1/(1+1))                 |       4 |
|  9 | 4/1        | 1+1+1+1                     |       4 |
| 10 | 1/5        | 1/(1+1+1+1+1)               |       6 |
| 11 | 5/1        | 1+1+1+1+1                   |       5 |
| 12 | 1/6        | 1/((1+1)*(1+1+1))           |       6 |
| 13 | 2/5        | (1+1)/(1+1+1+1+1)           |       7 |
| 14 | 3/4        | (1+1+1)/(1+1+1+1)           |       7 |
| 15 | 4/3        | 1+(1/(1+1+1))               |       5 |
| 16 | 5/2        | 1+1+(1/(1+1))               |       5 |
| 17 | 6/1        | (1+1)*(1+1+1)               |       5 |
| 18 | 1/7        | 1/((1+1+1)*(1+1) +1)        |       7 |
| 19 | 3/5        | (1+1+1)/(1+1+1+1+1)         |       8 |
| 20 | 5/3        | 1+((1+1)/(1+1+1))           |       6 |
| 21 | 7/1        | (1+1)*(1+1+1)+1             |       6 |
| 22 | 1/8        | 1/((1+1)*(1+1)*(1+1))       |       7 |
| 23 | 2/7        | (1+1)/((1+1)*(1+1+1)+1)     |       8 |
| 24 | 4/5        | (1+1+1+1)/(1+1+1+1+1)       |       9 |
| 25 | 5/4        | 1+(1/(1+1+1+1))             |       6 |
| 26 | 7/2        | 1+1+1+(1/(1+1))             |       6 |
| 27 | 8/1        | (1+1)*(1+1)*(1+1)           |       6 |
| 28 | 1/9        | 1/((1+1+1)*(1+1+1))         |       7 |
| 29 | 3/7        | (1+1+1)/((1+1+1)*(1+1) +1)  |       9 |
| 30 | 7/3        | 1+1+(1/(1+1+1))             |       6 |
| 31 | 9/1        | (1+1+1)*(1+1+1)             |       6 |
| 32 | 1/10       | 1/((1+1+1)*(1+1+1)+1)       |       8 |
| 33 | 2/9        | (1+1)/((1+1+1)*(1+1+1))     |       8 |
| 34 | 3/8        | (1+1+1)/((1+1)*(1+1)*(1+1)) |       9 |
| 35 | 4/7        | (1+1+1+1)/((1+1)*(1+1+1)+1) |      10 |
| 36 | 5/6        | (1/(1+1))+(1/(1+1+1))       |       7 |
| 37 | 6/5        | 1+(1/(1+1+1+1+1))           |       7 |
		

Crossrefs

Cf. A005245 (Mahler-Popken complexity).
Ordering used: A020652 (Cantor numerators), A020653 (Cantor denominators).