A025400 - OEIS

A025400

Numbers that are the sum of 3 distinct positive cubes in exactly 2 ways.

1009, 1366, 1457, 1520, 1737, 1756, 1793, 1854, 1945, 2072, 2241, 2456, 2736, 3060, 3592, 3599, 3745, 3926, 4105, 4131, 4168, 4229, 4320, 4376, 4437, 4447, 4473, 4616, 4733, 4922, 5130, 5435, 5472, 5643, 5706, 5825, 5832, 6183, 6301, 6642, 6848, 6904

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

OFFSET

1,1

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..10000

FORMULA

{n: A025469(n) = 2}. - R. J. Mathar, Jun 15 2018

MATHEMATICA

Reap[ For[n = 1, n <= 7000, n++, pr = Select[ PowersRepresentations[n, 3, 3], Times @@ # != 0 && Length[#] == Length[Union[#]] &] ; If[pr != {} && Length[pr] == 2, Print[n, pr]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Jul 31 2013 *)

Module[{nn=20}, Select[Tally[Total/@Subsets[Range[nn]^3, {3}]], #[[2]]==2 && #[[1]]<= nn^3-9&][[All, 1]]]//Union (* Harvey P. Dale, Apr 26 2020 *)

CROSSREFS

Cf. A025397 (not necessarily distinct)

Sequence in context: A261405 A325090 A024974 * A182695 A100776 A126238

Adjacent sequences: A025397 A025398 A025399 * A025401 A025402 A025403

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved