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A044453 Numbers k such that string 2,3 occurs in the base 4 representation of k but not of k+1.

%I A044453 #9 Nov 27 2021 04:52:31
%S A044453 11,27,47,59,75,91,111,123,139,155,191,203,219,239,251,267,283,303,
%T A044453 315,331,347,367,379,395,411,447,459,475,495,507,523,539,559,571,587,
%U A044453 603,623,635,651,667,767,779,795,815,827,843,859,879,891,907,923,959,971
%N A044453 Numbers k such that string 2,3 occurs in the base 4 representation of k but not of k+1.
%H A044453 Michael S. Branicky, <a href="/A044453/b044453.txt">Table of n, a(n) for n = 1..10000</a>
%o A044453 (Python)
%o A044453 from sympy.ntheory.factor_ import digits
%o A044453 def has23(n): return "23" in "".join(map(str, digits(n, 4)[1:]))
%o A044453 def ok(n): return has23(n) and not has23(n+1)
%o A044453 print([k for k in range(972) if ok(k)]) # _Michael S. Branicky_, Nov 27 2021
%Y A044453 Cf. A044072.
%K A044453 nonn,base
%O A044453 1,1
%A A044453 _Clark Kimberling_
%E A044453 a(48) and beyond from _Michael S. Branicky_, Nov 27 2021