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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 20 18:56 EDT 2019. Contains 326154 sequences. (Running on oeis4.)