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%I #15 Mar 28 2022 01:31:52
%S 0,1,2,3,4,5,6,9,10,11,12,18,19,20,22,25,36,37,38,44,45,50,51,52,74,
%T 75,76,77,89,90,100,101,102,105,109,147,150,153,154,165,166,173,178,
%U 179,180,181,204,205,210,212,214,217,293,294,299,300,301,306,308,309,329
%N Numbers without 3 consecutive equal digits in any base b >= 2.
%H Michael S. Branicky, <a href="/A178905/b178905.txt">Table of n, a(n) for n = 1..10000</a>
%t Prepend[Cases[Range[329], n_ /; NoneTrue[Range[2, (Sqrt[4 n - 3] - 1)/2], MatchQ[IntegerDigits[n, #], {___, d_, d_, d_, ___}] &]], 0] (* _Vladimir Reshetnikov_, Mar 20 2022 *)
%o (Python)
%o from sympy.ntheory.digits import digits
%o def three_in_a_row(s):
%o return any(s[i] == s[i+1] == s[i+2] for i in range(len(s) - 2))
%o def ok(n):
%o if n < 7: return True
%o b = 2
%o d = digits(n, b)[1:]
%o while len(d) >= 3:
%o if three_in_a_row(d): return False
%o b += 1
%o d = digits(n, b)[1:]
%o return True
%o print([k for k in range(331) if ok(k)]) # _Michael S. Branicky_, Mar 27 2022
%Y Cf. A063037.
%K base,nonn
%O 1,3
%A _Joonas Pohjonen_, Jun 22 2010
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