A135693 - OEIS

A135693

Numbers that are not the sum of three positive squares or cubes (which can be a mix of squares and cubes).

1, 2, 4, 5, 7, 8, 15, 23, 31, 87, 111, 119, 148, 167, 263, 311, 335, 391, 407, 455, 559, 599, 839, 951, 1159, 1231, 1287, 1303, 1391, 1455, 1463, 1607, 1660, 1679, 1751, 1863, 1991, 2351, 2615, 2799, 3247, 3983, 4327, 4367, 5199, 5655, 6047, 6159, 6351

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Presumably the sequence is finite.

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..82

MATHEMATICA

lim=40000; s=Range[Sqrt[lim]]^2; c=Range[Surd[lim, 3]]^3; A135693=Complement[Range[lim], Select[Total/@Tuples[Union[s, c], {3}], #<=lim&]] (* James C. McMahon, Apr 19 2025 *)

CROSSREFS

Cf. A113505, A135367.

Cf. A004214, A057904.

Sequence in context: A271505 A343915 A187054 * A135367 A141493 A103118

Adjacent sequences: A135690 A135691 A135692 * A135694 A135695 A135696

KEYWORD

nonn

AUTHOR

Zak Seidov and Giovanni Resta, Feb 24 2008

EXTENSIONS

Edited by N. J. A. Sloane, Mar 01 2008

Name clarified by James C. McMahon, Apr 19 2025 and Peter Munn, Dec 03 2025

STATUS

approved