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A033001 Every run of digits of n in base 3 has length 2. 31
4, 8, 36, 44, 72, 76, 328, 332, 396, 400, 652, 656, 684, 692, 2952, 2960, 2988, 2992, 3568, 3572, 3600, 3608, 5868, 5876, 5904, 5908, 6160, 6164, 6228, 6232, 26572, 26576, 26640, 26644, 26896, 26900, 26928, 26936, 32112, 32120 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
See A043291 for the base 2 version (which has a very simple formula), A033002 - A033014 for bases 4 through 16, A033015 - A033029 for the variants with runs of length >= 2. - M. F. Hasler, Feb 01 2014
LINKS
FORMULA
a(n)=4*A043307(n). - M. F. Hasler, Feb 01 2014
MATHEMATICA
Select[Range[10000], Union[Length/@Split[IntegerDigits[#, 3]]]=={2}&] (* Vincenzo Librandi, Feb 05 2014 *)
PROG
From M. F. Hasler, Feb 01 2014 (Start)
(PARI) is_A033001(n)=!until(!n\=9, bittest(4588304, n%27)||return)
(PARI) for(n=1, 9999, is_A033001(n)&&print1(n", ")) \\ (End)
(PARI) a(n) = my(v=binary(n+1)); v[1]=0; for(i=2, #v, v[i]+=(v[i]>=v[i-1])); 4*fromdigits(v, 9); \\ Kevin Ryde, Mar 13 2021
CROSSREFS
Sequence in context: A074736 A044829 A338086 * A269012 A149110 A354735
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified April 25 03:15 EDT 2024. Contains 371964 sequences. (Running on oeis4.)