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A004886 Numbers that are the sum of at most 2 positive 9th powers.

%I A004886 #56 Jul 06 2025 19:00:57
%S A004886 0,1,2,512,513,1024,19683,19684,20195,39366,262144,262145,262656,
%T A004886 281827,524288,1953125,1953126,1953637,1972808,2215269,3906250,
%U A004886 10077696,10077697,10078208,10097379,10339840,12030821,20155392,40353607,40353608
%N A004886 Numbers that are the sum of at most 2 positive 9th powers.
%H A004886 Zhuorui He, <a href="/A004886/b004886.txt">Table of n, a(n) for n = 1..10000</a>
%o A004886 (Python)
%o A004886 def A004886_upto(n):
%o A004886   a=set()
%o A004886   for i in range(n):
%o A004886     if 2*(i**9)>n: break
%o A004886     for j in range(i,n):
%o A004886       if i**9+j**9<=n: a.add(i**9+j**9)
%o A004886       else: break
%o A004886   return sorted(a) # _Zhuorui He_, Jun 30 2025
%o A004886 (PARI) lista(nn) = setbinop((x,y)->x^9+y^9, [0..nn]); \\ _Michel Marcus_, Jul 02 2025
%Y A004886 Cf. A001017 (9th powers), A003391 (sum of 2).
%K A004886 nonn
%O A004886 1,3
%A A004886 _N. J. A. Sloane_