|
|
A324037
|
|
The minimal number of iterations to reach 1 of the modified reduced Collatz function, defined for odd numbers 1 + 2*n in A324036 (assuming the Collatz conjecture).
|
|
2
|
|
|
0, 2, 1, 6, 7, 5, 3, 7, 4, 8, 2, 6, 9, 48, 7, 46, 10, 5, 8, 14, 47, 11, 6, 45, 9, 10, 4, 49, 12, 13, 8, 47, 10, 11, 5, 44, 50, 5, 9, 15, 9, 48, 3, 12, 12, 40, 7, 46, 51, 10, 10, 38, 16, 43, 49, 30, 4, 13, 8, 14, 41, 19, 47, 20, 52, 11, 11, 16, 39, 17, 6
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
The Collatz conjecture is that a(n) is finite. If 1 should never be reached then a(n) = -1.
Compare this sequence with the analogous one A075680(n+1) for the reduced Collatz map of A075677.
a(n) gives also the minimal number of iterations of the Vaillant-Delarue map f, defined in A324245, acting on n to reach 0 (assuming the Collatz conjecture).
For the link to the Vaillant-Delarue paper (where fs is called f_s) see A324036.
|
|
LINKS
|
|
|
FORMULA
|
fs^[a(n)](1 + 2*n) = 1 but fs^[a(n)-1](1 + 2*n) is not 1 (for all n with finite a(n)), where fs is the modified reduced Collatz map defined for 1 + 2*n in A324036(n), for n >= 1, and a(0) = 0.
|
|
EXAMPLE
|
a(4) = 7 because 1 + 2*4 = 9 and the 7 fs iterations acting on 9 are 7, 11, 17, 13, 3, 5, 1.
Compare this to the reduced Collatz map given in A075677 which needs only 6 = A075680(5) iterations 7, 11, 17, 13, 5, 1. The additional step in the fs case follows 13 == 5 mod(8).
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|