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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. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
PROG
(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)
print([k for k in range(972) if ok(k)]) # Michael S. Branicky, Nov 27 2021
CROSSREFS
Cf. A044072.
Sequence in context: A035701 A106839 A044072 * A212776 A362528 A137019
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
a(48) and beyond from Michael S. Branicky, Nov 27 2021
STATUS
approved

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Last modified April 13 12:32 EDT 2024. Contains 371641 sequences. (Running on oeis4.)