login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Triangle read by rows: T(n,k) (n >= 1, 1 <= k <= n) = length (or lifetime) of the meta-Fibonacci sequence f(1) = ... = f(n) = 1; f(i)=f(i-f(i-k))+f(i-f(i-n)) if that sequence is only defined for finitely many terms, or 0 if that sequence is infinite.
5

%I #19 Oct 25 2014 01:28:40

%S 6,0,14,164,54,13,0,0,10,11,60,37,11,12,13,2354,30,13,13,14,15,282,63,

%T 44,14,15,17,18,1336,368,31,15,17,18,19,20,100,47,49,17,18,19,20,21,

%U 22,1254,46,38,18,19,20,21,22,23,24,366,108,80,19,20,21,22,23

%N Triangle read by rows: T(n,k) (n >= 1, 1 <= k <= n) = length (or lifetime) of the meta-Fibonacci sequence f(1) = ... = f(n) = 1; f(i)=f(i-f(i-k))+f(i-f(i-n)) if that sequence is only defined for finitely many terms, or 0 if that sequence is infinite.

%C The zero entries (except T(4,1)) are only conjectural.

%D D. R. Hofstadter, Curious patterns and non-patterns in a family of meta-Fibonacci recursions, Lecture in Doron Zeilberger's Experimental Mathematics Seminar, Rutgers University, April 10 2014.

%H Lars Blomberg, <a href="/A240813/b240813.txt">Table of n, a(n) for n = 1..10000</a>, "infinity" = 10^8.

%H B. Balamohan, A. Kuznetsov and S. Tanny, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL10/Tanny/tanny3.html">On the behavior of a variant of Hofstadter's Q-sequence</a>, J. Integer Sequences, Vol. 10 (2007), #07.7.1.

%H D. R. Hofstadter, Curious patterns and non-patterns in a family of meta-Fibonacci recursions, Lecture in Doron Zeilberger's Experimental Mathematics Seminar, Rutgers University, April 10 2014; <a href="https://vimeo.com/91708646">Part 1</a>, <a href="https://vimeo.com/91710600">Part 2</a>.

%H <a href="/index/Ho#Hofstadter">Index entries for Hofstadter-type sequences</a>

%e Triangle begins:

%e 6,

%e 0, 14,

%e 164, 54, 13,

%e 0, 0, 10, 11,

%e 60, 37, 11, 12, 13,

%e 2354, 30, 13, 13, 14, 15,

%e 282, 63, 44, 14, 15, 17, 18,

%e 1336, 368, 31, 15, 17, 18, 19

%e ...

%Y Diagonals give A134680, A240811, A240812.

%Y See A240816 for another version.

%K nonn,tabl

%O 1,1

%A _N. J. A. Sloane_, Apr 15 2014

%E More terms from _Lars Blomberg_, Oct 24 2014