A280648 Numbers k such that k^3 has an odd number of digits and the middle digit is 8.

2, 24, 35, 38, 120, 127, 131, 138, 145, 172, 174, 182, 183, 208, 212, 215, 471, 481, 482, 485, 495, 505, 516, 517, 544, 551, 567, 594, 601, 610, 617, 621, 644, 646, 674, 677, 689, 736, 739, 749, 756, 768, 773, 774, 775, 776, 786, 799, 803, 812, 821, 830, 835

Offset

1,1

Comments

The sequence of cubes starts: 8, 13824, 42875, 54872, 1728000, 2048383, 2248091, 2628072, ...

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

2^3 = (8), 172^3 = 508(8)448, 610^3 = 2269(8)1000.

Mathematica

Select[Range[835], OddQ[len=Length[IntegerDigits[#^3]]]&&Part[IntegerDigits[#^3], (len+1)/2]==8 &] (* Stefano Spezia, Oct 03 2023 *)

Crossrefs

Cf. A280640-A280647, A280649, A181354.

See A279420-A279429 for a k^2 version.

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

Sequence in context: A212759 A112660 A330526 * A339403 A119066 A019996

Adjacent sequences: A280645 A280646 A280647 * A280649 A280650 A280651

Keyword

nonn,base,easy

Author

Lars Blomberg, Jan 07 2017

Status

approved