A283896 - OEIS

%I #4 Mar 19 2017 19:26:06

%S 91,2,180,2,180,2,180,2,180,2,180,2,180,2,180,2,180,2,180,2,180,2,180,

%T 2,180,2,180,2,180,2,180,2,180,2,180,2,180,2,180,2,180,2,180,2,180,2,

%U 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

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

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

%C 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.

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

%H Nathan Fox, <a href="/A283896/b283896.txt">Table of n, a(n) for n = 1..2467</a>

%p 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:

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

%K nonn,fini,full

%O 1,1

%A _Nathan Fox_, Mar 19 2017