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 A280649 Numbers k such that k^3 has an odd number of digits and the middle digit is 9. 12
 28, 33, 41, 108, 132, 157, 159, 175, 178, 181, 184, 187, 190, 193, 196, 204, 207, 209, 466, 474, 480, 486, 492, 508, 514, 515, 518, 519, 528, 536, 539, 552, 570, 588, 611, 627, 638, 648, 651, 657, 658, 659, 660, 706, 707, 708, 714, 719, 745, 757, 763, 765, 772 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The sequence of cubes starts: 21952, 35937, 68921, 1259712, 2299968, 3869893, 4019679, 5359375, ... LINKS Lars Blomberg, Table of n, a(n) for n = 1..10000 Jeremy Gardiner, Middle digit in cube numbers, Seqfan Mailing list, Dec 12 2016. EXAMPLE 28^3 = 21(9)52, 181^3 = 592(9)741, 536^3 = 1539(9)0656. MATHEMATICA ond9Q[n_]:=Module[{idn=IntegerDigits[n^3], len}, len=Length[idn]; OddQ[len]&&idn[[(len+1)/2]]==9]; Select[Range[800], ond9Q] (* Harvey P. Dale, Mar 14 2018 *) CROSSREFS Cf. A280640-A280648, A181354. See A279420-A279429 for a k^2 version. See A279430-A279431 for a k^2 version in base 2. Sequence in context: A230855 A090637 A261113 * A134657 A261106 A138687 Adjacent sequences:  A280646 A280647 A280648 * A280650 A280651 A280652 KEYWORD nonn,base,easy AUTHOR Lars Blomberg, Jan 07 2017 STATUS approved

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Last modified May 17 12:55 EDT 2021. Contains 343971 sequences. (Running on oeis4.)