A242594 Numbers k such that 4^k has initial digit 4.

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

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