A171489 a(n)=k is the smallest exponent k such that at least 4 equal decimal digits "n n n n" appear in the decimal representation of 2^k (n=0,1,...,9).

377, 313, 314, 219, 192, 41, 220, 181, 180, 421

Offset

0,1

References

Theo Kempermann, Zahlentheoretische Kostproben, Harri Deutsch, 2. aktualisierte Auflage 2005

Hugo Steinhaus, 100 neue Aufgaben: Elementare Mathematik, Urania Verlag Leipzig-Jena-Berlin 1973

Links

Table of n, a(n) for n=0..9.

Example

n=
0: 2^377 = 307828173409331868845930000782371982852185463050511302093346042220669701339821957901673955116288403443801781174272
1: 2^313 = 16687398718132110018711107079449625895333629080911349765211262561111091607661254297054391304192
2: 2^314 = 33374797436264220037422214158899251790667258161822699530422525122222183215322508594108782608384
3: 2^219 = 842498333348457493583344221469363458551160763204392890034487820288
4: 2^192 = 6277101735386680763835789423207666416102355444464034512896
5: 2^41 = 2199023255552
6: 2^220 = 1684996666696914987166688442938726917102321526408785780068975640576
7: 2^181 = 3064991081731777716716694054300618367237478244367204352
8: 2^180 = 1532495540865888858358347027150309183618739122183602176
9: 2^421 = 5415370496329716522614090203404460358274291162843391748379842930887932241807862544999950011922147613471467208908991351228465152
Theo Kempermann, Zahlentheoretische Kostproben, Harri Deutsch, 2. aktualisierte Auflage 2005

Crossrefs

Cf. A000079, A018802, A171132, A171242.

Sequence in context: A234916 A288916 A198640 * A105717 A352264 A222350

Adjacent sequences: A171486 A171487 A171488 * A171490 A171491 A171492

Keyword

fini,full,nonn,base

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Dec 10 2009

Status

approved