

A131537


Least power of 2 having exactly n consecutive 3's in its decimal representation.


0



5, 25, 83, 219, 221, 2270, 11020, 18843, 192915, 271978, 743748, 1039315, 13873203, 14060685
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OFFSET

1,1


COMMENTS

No more terms < 28*10^6.


LINKS

Table of n, a(n) for n=1..14.
Popular Computing (Calabasas, CA), Two Tables, Vol. 1, (No. 9, Dec 1973), page PC916.


EXAMPLE

a(3)=83 because 2^83(i.e. 9671406556917033397649408) is the smallest power of 2 to contain a run of 3 consecutive threes in its decimal form.


MATHEMATICA

a = ""; Do[ a = StringJoin[a, "3"]; b = StringJoin[a, "3"]; k = 1; While[ StringPosition[ ToString[2^k], a] == {}  StringPosition[ ToString[2^k], b] != {}, k++ ]; Print[k], {n, 1, 9} ]


CROSSREFS

Sequence in context: A264132 A147114 A296669 * A250555 A147122 A051229
Adjacent sequences: A131534 A131535 A131536 * A131538 A131539 A131540


KEYWORD

more,nonn,base


AUTHOR

Shyam Sunder Gupta, Aug 26 2007


EXTENSIONS

3 more terms from Sean A. Irvine, Jul 19 2010
a(13)a(14) from Lars Blomberg, Jan 24 2013


STATUS

approved



