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A131538
Exponent of least power of 2 having exactly n consecutive 4's in its decimal representation.
2
0, 2, 18, 44, 192, 315, 3396, 8556, 13327, 81785, 279267, 865357, 1799674, 1727603, 8760851, 63416791, 106892452
OFFSET
0,2
LINKS
Popular Computing (Calabasas, CA), Two Tables, Vol. 1, (No. 9, Dec 1973), page PC9-16.
EXAMPLE
a(3) = 44 because 2^44 (i.e. 17592186044416) is the smallest power of 2 to contain a run of 3 consecutive fours in its decimal form.
MATHEMATICA
a = ""; Do[ a = StringJoin[a, "4"]; b = StringJoin[a, "4"]; k = 1; While[ StringPosition[ ToString[2^k], a] == {} || StringPosition[ ToString[2^k], b] != {}, k++ ]; Print[k], {n, 1, 10} ]
CROSSREFS
Sequence in context: A296266 A365493 A280316 * A009820 A304933 A126909
KEYWORD
more,nonn,base
AUTHOR
Shyam Sunder Gupta, Aug 26 2007
EXTENSIONS
3 more terms from Sean A. Irvine, Jul 19 2010
a(14) from Lars Blomberg, Jan 24 2013
a(15) from Bert Dobbelaere, Feb 25 2019
a(16) from Paul Geneau de Lamarlière, Jun 26 2024
a(0)=0 prepended by Paul Geneau de Lamarlière, Jul 20 2024
STATUS
approved