

A217373


Numbers n the representation of which in base 3 ends in 2*k or 2*k+1 zeros, where k is odd.


1



9, 18, 27, 36, 45, 54, 63, 72, 90, 99, 108, 117, 126, 135, 144, 153, 171, 180, 189, 198, 207, 216, 225, 234, 252, 261, 270, 279, 288, 297, 306, 315, 333, 342, 351, 360, 369, 378, 387, 396, 414, 423, 432, 441, 450, 459, 468, 477, 495, 504, 513, 522, 531, 540
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OFFSET

1,1


COMMENTS

Or numbers having infinitary divisor 9, or the same having factor 9 in their FermiDirac factorization as product of distinct terms of A050376.


LINKS

Peter J. C. Moses, Table of n, a(n) for n = 1..10000
Index entries for 3automatic sequences.


FORMULA

a(n)/(10*n) tends to 1, as n goes to infinity.


MATHEMATICA

Select[Map[# Boole[IntegerQ[(1/4 (1+#))]IntegerQ[(1/4 (2+#))]&[Length[Last[Split[IntegerDigits[#, 3]]]]]]&, Range[3, 5000, 3]], #>0&] (* Peter J. C. Moses, Mar 20 2013 *)


CROSSREFS

Cf. A145204, A217319, A036554, A050376.
Sequence in context: A043453 A028439 A178896 * A033021 A031493 A020336
Adjacent sequences: A217370 A217371 A217372 * A217374 A217375 A217376


KEYWORD

nonn,easy


AUTHOR

Vladimir Shevelev, Mar 18 2013


STATUS

approved



