A283896 Relative of Hofstadter Q-sequence: a(-88) = 89, a(-87) = 2; thereafter a(n) = a(n-a(n-1)) + a(n-a(n-2)).

91, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180, 2, 180

Offset: 1

Author

Nathan Fox, Mar 19 2017

Keywords

• nonn
• fini
• full

Comments

In calculating terms of this sequence, use the convention that a(n)=0 for n<=-89.

Sequences like this are more naturally considered with the first nonzero term in position 1. But this sequence would then begin with 89 terms consisting entirely of alternating 2 and 89.

This sequence has exactly 2467 terms, since a(2467)=0 and computing a(2468) would refer to itself.

Links

• Nathan Fox, Table of n, a(n) for n = 1..2467

Crossrefs

Cf. A005185, A278066, A278067, A278068, A283893, A283894, A283895, A283897.

Programs

Maple

A283896:=proc(n) option remember: if n <= -89 then 0: elif n = -88 then 89: elif n = -87 then 2: else A283896(n-A283896(n-1)) + A283896(n-A283896(n-2)): fi: end: