A259092 Smallest k such that 2^k contains three adjacent copies of n in its decimal expansion.

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

Chai Wah Wu, Table of n, a(n) for n = 0..1000

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

Cf. A006889, A131535, A131536, A259089, A063565, A259091.

Sequence in context: A120377 A321821 A171242 * A060110 A113468 A220089

Adjacent sequences: A259089 A259090 A259091 * A259093 A259094 A259095

Keyword

nonn,base

Author

N. J. A. Sloane, Jun 18 2015

Extensions

More terms from Chai Wah Wu, Jun 18 2015

Status

approved