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A180089 Semiprimes which are the sum of three distinct positive cubes in two or more distinct ways. 3
1366, 1457, 1793, 1945, 3599, 4105, 5435, 7379, 8315, 9017, 10261, 10963, 11773, 12706, 13957, 15163, 15371, 15553, 15751, 15758, 16271, 17263, 17354, 17947, 18649, 19027, 19369, 19657, 19729, 19774, 19781, 19907, 21026, 21167, 22411 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

2^3+3^3+11^3=5^3+8^3+9^3=1366=2*683, 1^3+5^3+11^3=6^3+8^3+9^3=1457=31*47,..

LINKS

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

MATHEMATICA

f[n_]:=Last/@FactorInteger[n]=={1, 1}; lst={}; Do[Do[Do[If[f[p=a^3+b^3+c^3], AppendTo[lst, p]], {c, b-1, 1, -1}], {b, a-1, 1, -1}], {a, 55}]; lst1=Sort@lst; lst={}; Do[If[lst1[[n]]==lst1[[n+1]], AppendTo[lst, lst1[[n]]]], {n, Length[lst1]-1}]; lst

CROSSREFS

Cf. A011541, A024974, A025400, A122723, A180088

Sequence in context: A140936 A022204 A015405 * A020409 A231268 A192823

Adjacent sequences:  A180086 A180087 A180088 * A180090 A180091 A180092

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Aug 09 2010

STATUS

approved

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Last modified May 27 11:51 EDT 2017. Contains 287205 sequences.