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A348217 a(1) = 2; for n > 1, let d be the largest divisor of n appearing in all previous terms and k the largest value such that a(k) = d, then a(n) = n - k. 2
2, 1, 1, 3, 2, 2, 4, 1, 5, 1, 1, 5, 2, 1, 3, 9, 3, 2, 5, 1, 4, 4, 3, 2, 6, 2, 11, 6, 9, 2, 11, 10, 2, 1, 16, 7, 3, 5, 2, 8, 7, 1, 1, 13, 16, 7, 4, 3, 3, 18, 2, 8, 10, 4, 24, 4, 8, 7, 16, 7, 18, 11, 34, 5, 21, 4, 24, 5, 20, 17, 28, 5, 30, 23, 3, 10, 15, 34, 36, 11, 52, 31, 40, 13, 15, 35, 12, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
As n increases the terms generally remain scattered between 1 and n - see the linked image. However also present are lines of various gradients along which numerous terms are concentrated. These correspond to the distances back from a(n) to the last appearance of the terms like 1,2,3. These small terms become rare as n increases, e.g., in the first 10 millions terms, a(2849898) = 1 but then 1 does not appear again until a(6839757) = 1. In that range all terms where n is prime will have a(n) = n - 2849898.
LINKS
EXAMPLE
a(2) = 1 as the largest divisor of 2 so far appearing is 2, and that is 2 - 1 = 1 term back from 2.
a(3) = 1 as the largest divisor of 3 so far appearing is 1, and that is 3 - 2 = 1 term back from 3.
a(4) = 3 as the largest divisor of 4 so far appearing is 2, and that is 4 - 1 = 3 terms back from 4.
a(5) = 2 as the largest divisor of 5 so far appearing is 1, and that is 5 - 3 = 2 terms back from 5.
CROSSREFS
Sequence in context: A340381 A029259 A159266 * A290981 A161065 A161104
KEYWORD
nonn
AUTHOR
Scott R. Shannon, Oct 07 2021
STATUS
approved

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Last modified July 23 21:14 EDT 2024. Contains 374570 sequences. (Running on oeis4.)