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A044446
Numbers k such that string 1,0 occurs in the base-4 representation of k but not of k+1.
2
4, 20, 36, 52, 84, 100, 116, 132, 148, 164, 180, 196, 212, 228, 244, 340, 356, 372, 388, 404, 420, 436, 452, 468, 484, 500, 516, 532, 548, 564, 596, 612, 628, 644, 660, 676, 692, 708, 724, 740, 756, 772, 788, 804, 820, 852, 868, 884, 900, 916, 932, 948, 964
OFFSET
1,1
PROG
(Python)
from sympy.ntheory.factor_ import digits
def has10(k): s = "".join(map(str, digits(k, 4)[1:])); return "10" in s
def ok(n): return has10(n) and not has10(n+1)
print(list(filter(ok, range(965)))) # Michael S. Branicky, Apr 20 2021
CROSSREFS
KEYWORD
nonn,base
EXTENSIONS
a(5) = 68 removed by Georg Fischer, Jun 27 2019
STATUS
approved