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A044453
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Numbers k such that string 2,3 occurs in the base 4 representation of k but not of k+1.
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2
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11, 27, 47, 59, 75, 91, 111, 123, 139, 155, 191, 203, 219, 239, 251, 267, 283, 303, 315, 331, 347, 367, 379, 395, 411, 447, 459, 475, 495, 507, 523, 539, 559, 571, 587, 603, 623, 635, 651, 667, 767, 779, 795, 815, 827, 843, 859, 879, 891, 907, 923, 959, 971
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OFFSET
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1,1
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LINKS
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PROG
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(Python)
from sympy.ntheory.factor_ import digits
def has23(n): return "23" in "".join(map(str, digits(n, 4)[1:]))
def ok(n): return has23(n) and not has23(n+1)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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