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A271717
Integers n such that both n and n^3-1 are the sum of two positive cubes (see A003325).
0
9, 11664, 36864, 38134, 345744, 1750329, 4782969, 20820969, 47775744, 65804544, 95004009, 150994944, 448084224, 733055625, 1093955625, 1416167424
OFFSET
1,1
COMMENTS
Values of a^3 + b^3 such that (a^3 + b^3)^3 - 1 is of the form x^3 + y^3 where a, b, x, y > 0.
38134 = 2*23*829 is the first term that is nonsquare. What are the next square terms of this sequence?
n is a member of A007412 and n^3 is a member of A003072, obviously.
EXAMPLE
9 is a term because 9 = 1^3 + 2^3 and 9^3 - 1 = 6^3 + 8^3.
PROG
(PARI) isA003325(n) = for(k=1, sqrtnint(n\2, 3), ispower(n-k^3, 3) && return(1));
for(n=1, 1e7, if(isA003325(n) && isA003325(n^3-1), print1(n, ", ")));
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Altug Alkan, Apr 12 2016
EXTENSIONS
a(8)-a(16) from Chai Wah Wu, Apr 17 2016
STATUS
approved