OFFSET
1,2
COMMENTS
In the first 100000 terms the fixed points are 1, 2, 3, 6, 9, 10, 39, 91, 112; it is likely no more exist. The sequence is conjectured to be a permutation of the positive integers.
LINKS
Scott R. Shannon, Image for n = 1..100000. The green line is a(n) = n.
EXAMPLE
a(23) = 20 as a(21) + a(22) = 47 + 13 = 60, and 20 is the smallest unused number that shares a factor with 60 while the sum a(22) + 20 = 13 + 20 = 33 is distinct from all previous sums. Note that 18 is unused and shares a factor with 60 but the sum a(22) + 18 = 13 + 18 = 31 is the same as a(18) + a(19) = 15 + 16 = 31. This is the first term that differs from A337136.
CROSSREFS
KEYWORD
nonn
AUTHOR
Scott R. Shannon, Mar 08 2023
STATUS
approved