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Summarize the previous two terms!
1

%I #122 Nov 03 2024 06:15:38

%S 1,11,31,3113,3133,3153,215315,31123335,41225335,3132631435,

%T 313263243516,413283242536,31527334253618,3152733435261728,

%U 4152832445263728,3172634445263738,2162636435363738,2142934425663728,216273442566272819,319233542556372829

%N Summarize the previous two terms!

%C a(k) is found by counting the frequency of the digits in terms a(k-1) and a(k-2). Digits with zero frequency are not counted.

%C At n=54 the sequence enters a cycle of 46 terms so that for n>=100 we have a(k) = a(k-46). - _Lars Blomberg_, Jan 04 2014

%H Lars Blomberg, <a href="/A228530/b228530.txt">Table of n, a(n) for n = 1..145</a> containing the beginning and two full cycles.

%H <a href="http://www.reddit.com/r/puzzles/comments/1m2x6w/next_in_the_sequence/cc6wgsg?context=3">Original reddit post where this sequence was found.</a>

%e For n=5, a(5) is found by counting the frequency of the digits in the last two terms; there are three 1s and three 3s, so you get "three one three three", or 3133.

%Y Like A005151, but uses the previous two terms instead of just the previous term.

%K nonn,base,easy

%O 1,2

%A _Edison Y. He_, Sep 14 2013

%E Corrected a(8)-a(15), added a(16)-a(20) by _Lars Blomberg_, Jan 04 2014