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A259091
Smallest k such that 2^k contains two adjacent copies of n in its decimal expansion.
6
53, 40, 43, 25, 18, 16, 46, 24, 19, 33, 378, 313, 170, 374, 361, 359, 64, 34, 507, 151, 348, 246, 314, 284, 349, 314, 261, 151, 385, 166, 156, 364, 65, 219, 371, 359, 503, 148, 155, 352, 349, 308, 247, 255, 192, 387, 165, 149, 171, 150, 210, 155, 209, 101, 505
OFFSET
0,1
COMMENTS
The multi-digit generalization of A171132. - R. J. Mathar, Jul 06 2015
LINKS
Popular Computing (Calabasas, CA), Two Tables, Vol. 1, (No. 9, Dec 1973), page PC9-16.
EXAMPLE
2^53 = 9007199254740992 contains two adjacent 0's.
MATHEMATICA
Table[k = 0; While[! SequenceCount[IntegerDigits[2^k], Flatten[ConstantArray[IntegerDigits[n], 2]]] > 0, k++]; k, {n, 0, 100}] (* Robert Price, May 17 2019 *)
PROG
(Python)
def A259091(n):
s, k, k2 = str(n)*2, 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