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)).

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

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: A121642 A364087 A035886 * A043404 A015065 A097206

Adjacent sequences: A283896 A283897 A283898 * A283900 A283901 A283902

Keyword

nonn,fini,full

Author

Nathan Fox, Mar 19 2017

Status

approved