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A283887
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Relative of Hofstadter Q-sequence: a(n) = max(0, n+20830) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.
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5
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6, 20831, 20832, 20833, 9, 20834, 20835, 20836, 12, 20837, 20838, 20839, 15, 20840, 20841, 17, 20843, 18, 20843, 20845, 20846, 22, 21, 41671, 41665, 9, 18, 41680, 41683, 20839, 22, 20860, 20865, 20843, 27, 36, 20867, 41670, 20834, 39
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OFFSET
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1,1
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COMMENTS
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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 20830 terms.
Most terms in this sequence appear in one of two long patterns of 16 interleaved sequences. The first stretches from a(64180) through a(9029945). The second stretches from a(9029971) through a(-20830 + 84975*2^560362).
This sequence has exactly -20799 + 84975*2^560362 terms (of positive index). a(-20799 + 84975*2^560362) = 0, so an attempt to calculate a(-20798 + 84975*2^560362) would refer to itself.
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LINKS
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Nathan Fox, Table of n, a(n) for n = 1..68000
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FORMULA
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If the index is between 67 and 20831 (inclusive), then a(7n) = 7n+2, a(7n+1) = 7n+20832, a(7n+2) = 7n+20834, a(7n+3) = 7, a(7n+4) = 2n+41705, a(7n+5) = n+41653, a(7n+6) = 20828.
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MAPLE
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A283887:=proc(n) option remember: if n <= 0 then max(0, n+20830): else A283887(n-A283887(n-1)) + A283887(n-A283887(n-2)) + A283887(n-A283887(n-3)): fi: end:
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CROSSREFS
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Cf. A005185, A267501, A274058, A278055, A278066, A283884, A283885, A283886, A283888.
Sequence in context: A278369 A283886 A278653 * A241650 A337990 A143780
Adjacent sequences: A283884 A283885 A283886 * A283888 A283889 A283890
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KEYWORD
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nonn,fini
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AUTHOR
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Nathan Fox, Mar 19 2017
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STATUS
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approved
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