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A280645 Numbers k such that k^3 has an odd number of digits and the middle digit is 5. 3
26, 43, 107, 109, 119, 122, 136, 139, 144, 150, 177, 179, 197, 203, 205, 472, 476, 494, 499, 501, 506, 510, 523, 537, 555, 561, 563, 568, 583, 603, 608, 629, 636, 649, 664, 694, 696, 726, 752, 753, 762, 766, 769, 780, 795, 796, 807, 814, 819, 826, 831, 845 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence of cubes starts: 17576, 79507, 1225043, 1295029, 1685159, 1815848, 2515456, 2685619, ...

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

26^3 = 17(5)76, 150^3 = 337(5)000, 603^3 = 2192(5)6227

MATHEMATICA

Select[Range[900], OddQ[IntegerLength[#^3]]&&IntegerDigits[#^3][[(IntegerLength[ #^3]+1)/2]]==5&] (* Harvey P. Dale, Aug 24 2017 *)

CROSSREFS

Cf. A280640-A280644, A280646-A280649, A181354.

See A279420-A279429 for a k^2 version.

See A279430-A279431 for a k^2 version in base 2.

Sequence in context: A285513 A138727 A248404 * A260207 A130771 A217775

Adjacent sequences:  A280642 A280643 A280644 * A280646 A280647 A280648

KEYWORD

nonn,base,easy

AUTHOR

Lars Blomberg, Jan 07 2017

STATUS

approved

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Last modified May 18 04:22 EDT 2021. Contains 343994 sequences. (Running on oeis4.)