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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..53.

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

Cf. A007090, A097357, A085805, A043880.

Sequence in context: A238764 A085805 A119413 * A232221 A323183 A072977

Adjacent sequences:  A044443 A044444 A044445 * A044447 A044448 A044449

KEYWORD

nonn,base

AUTHOR

Clark Kimberling

EXTENSIONS

a(5) = 68 removed by Georg Fischer, Jun 27 2019

STATUS

approved

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Last modified January 22 00:08 EST 2022. Contains 350481 sequences. (Running on oeis4.)