A280644 Numbers k such that k^3 has an odd number of digits and the middle digit is 4.

7, 104, 112, 140, 143, 158, 166, 186, 188, 195, 465, 467, 490, 541, 558, 572, 595, 598, 604, 605, 606, 607, 613, 616, 622, 625, 630, 634, 635, 640, 643, 647, 653, 667, 675, 679, 687, 702, 712, 718, 720, 727, 734, 738, 759, 764, 783, 787, 802, 810, 815, 818

Offset

1,1

Comments

The sequence of cubes starts: 343, 1124864, 1404928, 2744000, 2924207, 3944312, 4574296, 6434856, ...

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

7^3 = 3(4)3, 195^3 = 741(4)875, 640^3 = 2621(4)4000

Mathematica

Select[Range[1000], OddQ[IntegerLength[#^3]]&&NumberDigit[#^3, (IntegerLength[ #^3]-1)/2]==4&] (* Harvey P. Dale, Aug 12 2021 *)

Crossrefs

Cf. A280640-A280643, A280645-A280649, A181354.

See A279420-A279429 for a k^2 version.

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

Sequence in context: A318398 A318815 A195246 * A322646 A224706 A001921

Adjacent sequences: A280641 A280642 A280643 * A280645 A280646 A280647

Keyword

nonn,base,easy

Author

Lars Blomberg, Jan 07 2017

Status

approved