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Numbers whose square can be expressed as the sum of two positive cubes in at least 3 ways.
4

%I #14 May 27 2016 12:38:57

%S 3343221000,26745768000,90266967000

%N Numbers whose square can be expressed as the sum of two positive cubes in at least 3 ways.

%C Although this sequence has keyword "bref", this sequence is infinite since if n is in this sequence, then n*k^3 is in this sequence for all k > 0. - _Altug Alkan_, May 10 2016

%H Uwe Hollerbach, <a href="http://www.korgwal.com/ramanujan/">Taxi, Taxi!</a> [Original link, broken]

%H Uwe Hollerbach, <a href="http://web.archive.org/web/20120203221114/http://www.korgwal.com/ramanujan">Taxi, Taxi!</a> [Replacement link to Wayback Machine]

%H Uwe Hollerbach, <a href="/A003825/a003825.html">Taxi! Taxi!</a> [Cached copy from Wayback Machine, html version of top page only]

%F a(n) = sqrt(A155960(n)).

%e a(1)=3343221000 where 3343221000^2 = 279300^3 + 2234400^3 = 790020^3 + 2202480^3 = 1256850^3 + 2094750^3.

%Y Cf. A051302, A155960.

%K nonn,hard,more,bref

%O 1,1

%A _Ray Chandler_, Jan 31 2009