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A283886
Relative of Hofstadter Q-sequence: a(n) = max(0, n+19395) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.
5
6, 19396, 19397, 19398, 9, 19399, 19400, 19401, 12, 19402, 19403, 19404, 15, 19405, 19406, 17, 19408, 18, 19408, 19410, 19411, 22, 21, 38801, 38795, 9, 18, 38810, 38813, 19404, 22, 19425, 19430, 19408, 27, 36, 19432, 38800, 19399, 39
OFFSET
1,1
COMMENTS
Sequences like this are more naturally considered with the first nonzero term in position 1. But this sequence would then match A000027 for its first 19395 terms.
Most terms in this sequence appear in a long pattern stretching from a(58340) through a(80425266), of 16 interleaved sequences.
This sequence has exactly 80425397 terms (of positive index). a(80425397) = 0, so an attempt to calculate a(80425398) would refer to itself.
FORMULA
If the index is between 67 and 19396 (inclusive), then a(7n) = 7n+2, a(7n+1) = 7n+19397, a(7n+2) = 7n+19399, a(7n+3) = 7, a(7n+4) = 2n+38835, a(7n+5) = n+38783, a(7n+6) = 19393.
MAPLE
A283886:=proc(n) option remember: if n <= 0 then max(0, n+19395): else A283886(n-A283886(n-1)) + A283886(n-A283886(n-2)) + A283886(n-A283886(n-3)): fi: end:
KEYWORD
nonn,fini
AUTHOR
Nathan Fox, Mar 19 2017
STATUS
approved