cp's OEIS Frontend

A171132 The smallest exponent k such that the digit n appears at two adjacent places in the decimal representation of 2^k.

%I A171132 #2 Mar 30 2012 17:40:15
%S A171132 53,40,43,25,18,16,46,24,19,33
%N A171132 The smallest exponent k such that the digit n appears at two adjacent places in the decimal representation of 2^k.
%D A171132 Helmut Kracke, Mathe-musische Knobelisken, Duemmler Bonn, 2. Auflage 1983
%H A171132 Theo Kempermann, <a href="http://www.harri-deutsch.de/verlag/titel/kemperma/s_1692.htm">Zahlentheoretische Kostproben</a>, Harri Deutsch, 2. aktualisierte Auflage 2005
%e A171132 n=0: 2^53 = 9007199254740992, digit 0 duplicated at 9(00)7199254..
%e A171132 n=1: 2^40 = 1099511627776, digit 1 duplicated at 10995(11)627776..
%e A171132 n=2: 2^43 = 8796093022208, digit 2 duplicated even twice
%e A171132 n=3: 2^25 = 33554432, digit 3 duplicated at (33)554432
%e A171132 n=4: 2^18 = 262144
%e A171132 n=5: 2^16 = 65536
%e A171132 n=6: 2^46 = 70368744177664
%e A171132 n=7: 2^24 = 16777216
%e A171132 n=8: 2^19 = 524288
%e A171132 n=9: 2^33 = 8589934592
%Y A171132 Cf. A000079, A018802.
%K A171132 nonn,fini,full,base
%O A171132 1,1
%A A171132 Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Dec 04 2009
%E A171132 Definition simplified, keyword:base,full added - _R. J. Mathar_, Dec 07 2009