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A242594 Numbers k such that 4^k has initial digit 4. 2
1, 6, 11, 16, 21, 26, 31, 36, 41, 46, 99, 104, 109, 114, 119, 124, 129, 134, 139, 144, 197, 202, 207, 212, 217, 222, 227, 232, 237, 242, 295, 300, 305, 310, 315, 320, 325, 330, 335, 393, 398, 403, 408, 413, 418, 423, 428, 433, 491, 496, 501, 506, 511, 516, 521, 526, 531, 584, 589, 594, 599, 604, 609, 614, 619 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..9693

FORMULA

a(n) = log_4(A067482(n)).

EXAMPLE

6 is in the sequence because 4^6 = 4096 starts with 4.

MAPLE

select(t -> 4^t >= 4*10^ilog10(4^t) and 4^t < 5*10^ilog10(4^t), [$1..1000]); # Robert Israel, May 18 2014

CROSSREFS

Cf. A067482.

Sequence in context: A140232 A315467 A315468 * A315469 A315470 A184487

Adjacent sequences:  A242591 A242592 A242593 * A242595 A242596 A242597

KEYWORD

nonn,base

AUTHOR

Robert Israel, May 18 2014

STATUS

approved

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Last modified October 18 08:27 EDT 2021. Contains 348067 sequences. (Running on oeis4.)