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

Author

Arkadiusz Wesolowski, Aug 23 2013

Keywords

• nonn

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

• Wikipedia, Prime power

Crossrefs

Cf. A020898, A025473. Subsequence of A061345.

Programs

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, ", "))));