

A274128


Numbers n such that n and n^2 are both a sum of two positive cubes.


1



39312, 251370, 314496, 432523, 948051, 1061424, 1536416, 2010960, 2515968, 3009825, 3460184, 4914000, 6786990, 6822900, 7154784, 7584408, 7825545, 8491392, 11678121, 12291328, 13484016, 16087680, 20127744, 24078600, 25501762, 25597377
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OFFSET

1,1


COMMENTS

Numbers n such that n^k is the sum of two positive cubes for all k not divisible by 3.
The restriction on the values of k is the result of Fermat's Last Theorem.
Inspiration was Taxicab number 39312. It is the least number with the property that sequence focuses on.


LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..1646


EXAMPLE

251370 is a term because 251370 = 29^3 + 61^3 and 251370^2 = 2961^3 + 3339^3.


PROG

(PARI) isA003325(n) = for(k=1, sqrtnint(n\2, 3), ispower(nk^3, 3) && return(1));
lista(nn) = for(n=1, nn, if(isA003325(n) && isA003325(n^2), print1(n, ", ")));


CROSSREFS

Cf. A003325.
Sequence in context: A250515 A031667 A196200 * A144306 A234033 A253940
Adjacent sequences: A274125 A274126 A274127 * A274129 A274130 A274131


KEYWORD

nonn


AUTHOR

Altug Alkan, Jun 10 2016


STATUS

approved



