A180089 Semiprimes which are the sum of three distinct positive cubes in two or more distinct ways.

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

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: A015405 A295466 A292780 * A020409 A231268 A192823

Adjacent sequences: A180086 A180087 A180088 * A180090 A180091 A180092

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Aug 09 2010

Status

approved