|
%I #18 May 17 2019 14:43:48
%S 53,40,43,25,18,16,46,24,19,33,378,313,170,374,361,359,64,34,507,151,
%T 348,246,314,284,349,314,261,151,385,166,156,364,65,219,371,359,503,
%U 148,155,352,349,308,247,255,192,387,165,149,171,150,210,155,209,101,505
%N Smallest k such that 2^k contains two adjacent copies of n in its decimal expansion.
%C The multi-digit generalization of A171132. - _R. J. Mathar_, Jul 06 2015
%H Chai Wah Wu, <a href="/A259091/b259091.txt">Table of n, a(n) for n = 0..1000</a>
%H Popular Computing (Calabasas, CA), <a href="/A094776/a094776.jpg">Two Tables</a>, Vol. 1, (No. 9, Dec 1973), page PC9-16.
%e 2^53 = 9007199254740992 contains two adjacent 0's.
%t Table[k = 0; While[! SequenceCount[IntegerDigits[2^k], Flatten[ConstantArray[IntegerDigits[n], 2]]] > 0, k++]; k, {n, 0, 100}] (* _Robert Price_, May 17 2019 *)
%o (Python)
%o def A259091(n):
%o ....s, k, k2 = str(n)*2, 0, 1
%o ....while True:
%o ........if s in str(k2):
%o ............return k
%o ........k += 1
%o ........k2 *= 2 # _Chai Wah Wu_, Jun 18 2015
%Y Cf. A006889, A131535, A131536, A259089, A063565, A259092.
%K nonn,base
%O 0,1
%A _N. J. A. Sloane_, Jun 18 2015
%E More terms from _Chai Wah Wu_, Jun 18 2015
|
