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A228485
Odd prime powers p^k such that p is congruent to 2 or 5 mod 9.
1
5, 11, 23, 25, 29, 41, 47, 59, 83, 101, 113, 121, 125, 131, 137, 149, 167, 173, 191, 227, 239, 257, 263, 281, 293, 311, 317, 347, 353, 383, 389, 401, 419, 443, 461, 479, 491, 509, 529, 563, 569, 587, 599, 617, 625, 641, 653, 659, 677, 743, 761, 797, 821, 839
OFFSET
1,1
COMMENTS
For any n, the equation x^3 + y^3 = a(n)*z^3 is not solvable in nonzero integers. Therefore, these numbers do not occur in A020898.
REFERENCES
Henri Cohen, Number Theory. Volume I: Tools and Diophantine Equations, Graduate Texts in Mathematics 239, Springer, 2007, pp. 374-375.
PROG
(PARI) forstep(n=3, 839, 2, p=isprimepower(n); if(p>0, m=Mod(round(n^(1/p)), 9); if(m==2||m==5, print1(n, ", "))));
CROSSREFS
Cf. A020898, A025473. Subsequence of A061345.
Sequence in context: A189978 A192761 A152533 * A161896 A317909 A304372
KEYWORD
nonn
AUTHOR
STATUS
approved