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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 *.

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%I A373701 #13 Jul 06 2024 13:45:51
%S A373701 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,
%T A373701 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,
%U A373701 9,10,12,12,8,9,8,8,9,11,13,12,9,8,8,8,9,10
%N 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 *.
%C A373701 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.
%H A373701 Dimitri Zucker, <a href="https://www.youtube.com/watch?v=RdnTi-2gahs">The Most Underrated Concept in Number Theory</a>, Combo Class Youtube video.
%e A373701 |    | rational   |  minimal expression         |    a(n) |
%e A373701 |---:|:-----------|:----------------------------|--------:|
%e A373701 |  1 | 1/1        | 1                           |       1 |
%e A373701 |  2 | 1/2        | 1/(1+1)                     |       3 |
%e A373701 |  3 | 2/1        | 1+1                         |       2 |
%e A373701 |  4 | 1/3        | 1/(1+1+1)                   |       4 |
%e A373701 |  5 | 3/1        | 1+1+1                       |       3 |
%e A373701 |  6 | 1/4        | 1/(1+1+1+1)                 |       5 |
%e A373701 |  7 | 2/3        | (1+1)/(1+1+1)               |       5 |
%e A373701 |  8 | 3/2        | 1+(1/(1+1))                 |       4 |
%e A373701 |  9 | 4/1        | 1+1+1+1                     |       4 |
%e A373701 | 10 | 1/5        | 1/(1+1+1+1+1)               |       6 |
%e A373701 | 11 | 5/1        | 1+1+1+1+1                   |       5 |
%e A373701 | 12 | 1/6        | 1/((1+1)*(1+1+1))           |       6 |
%e A373701 | 13 | 2/5        | (1+1)/(1+1+1+1+1)           |       7 |
%e A373701 | 14 | 3/4        | (1+1+1)/(1+1+1+1)           |       7 |
%e A373701 | 15 | 4/3        | 1+(1/(1+1+1))               |       5 |
%e A373701 | 16 | 5/2        | 1+1+(1/(1+1))               |       5 |
%e A373701 | 17 | 6/1        | (1+1)*(1+1+1)               |       5 |
%e A373701 | 18 | 1/7        | 1/((1+1+1)*(1+1) +1)        |       7 |
%e A373701 | 19 | 3/5        | (1+1+1)/(1+1+1+1+1)         |       8 |
%e A373701 | 20 | 5/3        | 1+((1+1)/(1+1+1))           |       6 |
%e A373701 | 21 | 7/1        | (1+1)*(1+1+1)+1             |       6 |
%e A373701 | 22 | 1/8        | 1/((1+1)*(1+1)*(1+1))       |       7 |
%e A373701 | 23 | 2/7        | (1+1)/((1+1)*(1+1+1)+1)     |       8 |
%e A373701 | 24 | 4/5        | (1+1+1+1)/(1+1+1+1+1)       |       9 |
%e A373701 | 25 | 5/4        | 1+(1/(1+1+1+1))             |       6 |
%e A373701 | 26 | 7/2        | 1+1+1+(1/(1+1))             |       6 |
%e A373701 | 27 | 8/1        | (1+1)*(1+1)*(1+1)           |       6 |
%e A373701 | 28 | 1/9        | 1/((1+1+1)*(1+1+1))         |       7 |
%e A373701 | 29 | 3/7        | (1+1+1)/((1+1+1)*(1+1) +1)  |       9 |
%e A373701 | 30 | 7/3        | 1+1+(1/(1+1+1))             |       6 |
%e A373701 | 31 | 9/1        | (1+1+1)*(1+1+1)             |       6 |
%e A373701 | 32 | 1/10       | 1/((1+1+1)*(1+1+1)+1)       |       8 |
%e A373701 | 33 | 2/9        | (1+1)/((1+1+1)*(1+1+1))     |       8 |
%e A373701 | 34 | 3/8        | (1+1+1)/((1+1)*(1+1)*(1+1)) |       9 |
%e A373701 | 35 | 4/7        | (1+1+1+1)/((1+1)*(1+1+1)+1) |      10 |
%e A373701 | 36 | 5/6        | (1/(1+1))+(1/(1+1+1))       |       7 |
%e A373701 | 37 | 6/5        | 1+(1/(1+1+1+1+1))           |       7 |
%Y A373701 Cf. A005245 (Mahler-Popken complexity).
%Y A373701 Ordering used: A020652 (Cantor numerators), A020653 (Cantor denominators).
%K A373701 nonn
%O A373701 1,2
%A A373701 _Adil Soubki_, Jun 13 2024