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 A171132 The smallest exponent k such that the digit n appears at two adjacent places in the decimal representation of 2^k. 8
 53, 40, 43, 25, 18, 16, 46, 24, 19, 33 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES Helmut Kracke, Mathe-musische Knobelisken, Duemmler Bonn, 2. Auflage 1983 LINKS Theo Kempermann, Zahlentheoretische Kostproben, Harri Deutsch, 2. aktualisierte Auflage 2005 EXAMPLE n=0: 2^53 = 9007199254740992, digit 0 duplicated at 9(00)7199254.. n=1: 2^40 = 1099511627776, digit 1 duplicated at 10995(11)627776.. n=2: 2^43 = 8796093022208, digit 2 duplicated even twice n=3: 2^25 = 33554432, digit 3 duplicated at (33)554432 n=4: 2^18 = 262144 n=5: 2^16 = 65536 n=6: 2^46 = 70368744177664 n=7: 2^24 = 16777216 n=8: 2^19 = 524288 n=9: 2^33 = 8589934592 CROSSREFS Cf. A000079, A018802. Sequence in context: A048606 A033373 A289237 * A259091 A104936 A262908 Adjacent sequences:  A171129 A171130 A171131 * A171133 A171134 A171135 KEYWORD nonn,fini,full,base AUTHOR Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Dec 04 2009 EXTENSIONS Definition simplified, keyword:base,full added - R. J. Mathar, Dec 07 2009 STATUS approved

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