cp's OEIS Frontend

A283894 Relative of Hofstadter Q-sequence: a(1) = 17, a(2) = 2; thereafter a(n) = a(n-a(n-1)) + a(n-a(n-2)).

%I A283894 #6 Mar 19 2017 19:25:57
%S A283894 17,2,17,2,17,2,17,2,17,2,17,2,17,2,17,2,17,19,2,36,2,36,2,36,2,36,2,
%T A283894 36,2,36,2,36,2,36,2,36,19,4,38,38,34,4,55,38,17,4,91,38,17,4,127,38,
%U A283894 17,21,40,4,34,57,4,21,72,34,2,70,2,70,2,70,2,70,19,19,42,76,2
%N A283894 Relative of Hofstadter Q-sequence: a(1) = 17, a(2) = 2; thereafter a(n) = a(n-a(n-1)) + a(n-a(n-2)).
%C A283894 In calculating terms of this sequence, use the convention that a(n)=0 for n <= 0.
%C A283894 Most terms in this sequence alternate between 2 and a large number. Such runs of terms are separated by 102 other terms, and each run is approximately twice as long as the previous.
%H A283894 Nathan Fox, <a href="/A283894/b283894.txt">Table of n, a(n) for n = 1..10000</a>
%F A283894 For nonnegative integers i, if 1 <= 2n + r <= 594*2^(i+1) - 2, then
%F A283894 a(594*2^i + 100 + 2n) = 2
%F A283894 a(594*2^i + 100 + 2n + 1) = 594*2^(i+1) - 2.
%p A283894 A283894:=proc(n) option remember: if n <= 0 then 0: elif n = 1 then 17: elif n = 2 then 2: else A283894(n-A283894(n-1)) + A283894(n-A283894(n-2)): fi: end:
%Y A283894 Cf. A005185, A278066, A278067, A278068, A283893, A283895, A283896, A283897.
%K A283894 nonn
%O A283894 1,1
%A A283894 _Nathan Fox_, Mar 19 2017