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A273943 Put and say how often: a(n) = n/2 if n is even, else a(n) = number of matches of "a(n-1)" in the concatenation of all "a(i)" with i < n, where "x" denotes the decimal string of x. 2
0, 1, 1, 2, 2, 2, 3, 1, 4, 1, 5, 1, 6, 1, 7, 1, 8, 1, 9, 1, 10, 1, 11, 4, 12, 2, 13, 1, 14, 3, 15, 2, 16, 2, 17, 2, 18, 2, 19, 2, 20, 1, 21, 6, 22, 5, 23, 2, 24, 1, 25, 2, 26, 1, 27, 1, 28, 1, 29, 1, 30, 1, 31, 4, 32, 2, 33, 1, 34, 1, 35, 1, 36, 1, 37, 1, 38, 1, 39, 1, 40, 1, 41, 5, 42, 1, 43, 3, 44, 1, 45, 1, 46, 1, 47, 1, 48, 1, 49, 1, 50, 1, 51, 4, 52, 4, 53, 1, 54, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Inspired by Look-and-Say sequences.

LINKS

Rainer Rosenthal, Table of n, a(n) for n = 0..106473

EXAMPLE

a(4) = 2 by definition and a(5) = 2 because "2" appears twice in the string built from the first 5 entries, i.e. "01122".

Nice question: how to continue 0112223141516171819110111? Answer: 4, since 11 was put last and there are 4 occurences of 11 so far.

MAPLE

rev:=proc(f)local i, fr; fr:=[]; for i to nops(f) do fr:=[op(fr), f[-i]]od; return fr; end:mc := z->`if`(z=0, [0], rev(convert(z, base, 10))):

matches := proc(f, z)local i, t, cnt; t:=mc(z); cnt:=0; for i to nops(f)+1-nops(t)do if f[i..i+nops(t)-1]=t then cnt := cnt+1; fi; od; return cnt; end:

addZ := proc(f, z)local t; t:=mc(z); return[op(f), op(t)]; end:

s:=[]:a:=[]:for i from 0 to 54 do s:=addZ(s, i); m:=matches(s, i); s:=addZ(s, m); a:=[op(a), i, m]; od:seq(a[i+1], i=0..109);

CROSSREFS

Cf. A005150, A225212.

See A274013 for bisection a(2k+1).

Sequence in context: A141059 A135151 A256855 * A256071 A248808 A233206

Adjacent sequences:  A273940 A273941 A273942 * A273944 A273945 A273946

KEYWORD

nonn,base,easy

AUTHOR

Rainer Rosenthal, Jun 05 2016

STATUS

approved

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Last modified February 18 02:57 EST 2020. Contains 332006 sequences. (Running on oeis4.)