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A003398 Numbers that are the sum of 9 positive 9th powers.

%I A003398 #23 Jun 22 2025 04:03:18
%S A003398 9,520,1031,1542,2053,2564,3075,3586,4097,4608,19691,20202,20713,
%T A003398 21224,21735,22246,22757,23268,23779,39373,39884,40395,40906,41417,
%U A003398 41928,42439,42950,59055,59566,60077,60588,61099,61610,62121,78737,79248,79759,80270,80781,81292,98419
%N A003398 Numbers that are the sum of 9 positive 9th powers.
%H A003398 David A. Corneth, <a href="/A003398/b003398.txt">Table of n, a(n) for n = 1..10000</a>
%e A003398 From _David A. Corneth_, Aug 02 2020: (Start)
%e A003398 26015282 is in the sequence as 26015282 = 1^9 + 1^9 + 1^9 + 2^9 + 5^9 + 5^9 + 5^9 + 6^9 + 6^9.
%e A003398 56248367 is in the sequence as 56248367 = 2^9 + 5^9 + 5^9 + 5^9 + 6^9 + 6^9 + 6^9 + 6^9 + 6^9.
%e A003398 84613980 is in the sequence as 84613980 = 1^9 + 1^9 + 1^9 + 1^9 + 2^9 + 5^9 + 5^9 + 7^9 + 7^9. (End)
%t A003398 M = 10^5; m = M^(1/9) // Ceiling; Reap[
%t A003398 For[a = 1, a <= m, a++,
%t A003398 For[b = a, b <= m, b++, For[c = b, c <= m, c++, For[d = c, d <= m, d++,
%t A003398 For[e = d, e <= m, e++, For[f = e, f <= m, f++, For[g = f, g <= m, g++,
%t A003398 For[h = g, h <= m, h++, For[i = h, i <= m, i++,
%t A003398 s = a^9 + b^9 + c^9 + d^9 + e^9 + f^9 + g^9 + h^9 + i^9;
%t A003398 If[s <= M, Sow[s]]]]]]]]]]]][[2, 1]] // Union (* _Jean-François Alcover_, Dec 01 2020 *)
%Y A003398 Cf. A001017 (9th powers).
%Y A003398 Column k=9 of A336725.
%K A003398 nonn,easy
%O A003398 1,1
%A A003398 _N. J. A. Sloane_