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A259092
Smallest k such that 2^k contains three adjacent copies of n in its decimal expansion.
6
242, 42, 43, 83, 44, 41, 157, 24, 39, 50, 949, 1841, 3661, 1798, 1701, 1161, 1806, 391, 1890, 2053, 950, 1164, 2354, 1807, 3816, 1800, 1799, 818, 1702, 2115, 904, 1798, 1807, 2270, 392, 1699, 3022, 394, 2054, 1758, 1804, 2300, 2720, 2403, 3396, 1133, 1808, 3820
OFFSET
0,1
COMMENTS
The multi-digit generalization of A171242. - R. J. Mathar, Jul 06 2015
LINKS
Popular Computing (Calabasas, CA), Two Tables, Vol. 1, (No. 9, Dec 1973), page PC9-16.
EXAMPLE
2^242 = 7067388259113537318333190002971674063309935587502475832486424805170479104 contains three adjacent 0's.
MATHEMATICA
Table[k = 0; While[! SequenceCount[IntegerDigits[2^k], Flatten[ConstantArray[IntegerDigits[n], 3]]] > 0, k++]; k, {n, 0, 50}] (* Robert Price, May 17 2019 *)
PROG
(Python)
def A259092(n):
s, k, k2 = str(n)*3, 0, 1
while True:
if s in str(k2):
return k
k += 1
k2 *= 2 # Chai Wah Wu, Jun 18 2015
CROSSREFS
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Jun 18 2015
EXTENSIONS
More terms from Chai Wah Wu, Jun 18 2015
STATUS
approved