A228485 Odd prime powers p^k such that p is congruent to 2 or 5 mod 9.

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.

Links

Table of n, a(n) for n=1..54.

Wikipedia, Prime power

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

Adjacent sequences: A228482 A228483 A228484 * A228486 A228487 A228488

Keyword

nonn

Author

Arkadiusz Wesolowski, Aug 23 2013

Status

approved