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A283899 Relative of Hofstadter Q-sequence: a(-399) = 400, a(-398) = 4, a(-397) = 400, a(-396) = 4; thereafter a(n) = a(n-a(n-1)) + a(n-a(n-2)). 5
800, 4, 400, 8, 800, 4, 400, 12, 800, 4, 400, 16, 800, 4, 400, 20, 800, 4, 400, 24, 800, 4, 400, 28, 800, 4, 400, 32, 800, 4, 400, 36, 800, 4, 400, 40, 800, 4, 400, 44, 800, 4, 400, 48, 800, 4, 400, 52, 800, 4, 400, 56, 800, 4, 400, 60 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

In calculating terms of this sequence, use the convention that a(n)=0 for n<=-400.

Sequences like this are more naturally considered with the first nonzero term in position 1. But this sequence would then begin with 400 terms consisting entirely of alternating 4 and 400.

This sequence has exactly 465 terms, since a(465)=0 and computing a(466) would refer to itself.

LINKS

Nathan Fox, Table of n, a(n) for n = 1..465

MAPLE

A283899:=proc(n) option remember: if n <= -400 then 0: elif n = -399 then 400: elif n = -398 then 4: elif n = -397 then 400: elif n = -396 then 4: else A283899(n-A283899(n-1)) + A283899(n-A283899(n-2)): fi: end:

CROSSREFS

Cf. A005185, A283898, A283900, A283901, A283902.

Sequence in context: A101039 A121642 A035886 * A043404 A015065 A097206

Adjacent sequences:  A283896 A283897 A283898 * A283900 A283901 A283902

KEYWORD

nonn,fini,full

AUTHOR

Nathan Fox, Mar 19 2017

STATUS

approved

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Last modified December 2 13:15 EST 2021. Contains 349443 sequences. (Running on oeis4.)