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A228530
Summarize the previous two terms!
1
1, 11, 31, 3113, 3133, 3153, 215315, 31123335, 41225335, 3132631435, 313263243516, 413283242536, 31527334253618, 3152733435261728, 4152832445263728, 3172634445263738, 2162636435363738, 2142934425663728, 216273442566272819, 319233542556372829
OFFSET
1,2
COMMENTS
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.
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
LINKS
Lars Blomberg, Table of n, a(n) for n = 1..145 containing the beginning and two full cycles.
EXAMPLE
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.
CROSSREFS
Like A005151, but uses the previous two terms instead of just the previous term.
Sequence in context: A143765 A023306 A068839 * A177360 A060857 A045982
KEYWORD
nonn,base,easy,changed
AUTHOR
Edison Y. He, Sep 14 2013
EXTENSIONS
Corrected a(8)-a(15), added a(16)-a(20) by Lars Blomberg, Jan 04 2014
STATUS
approved