A003392 - OEIS

%I #18 Aug 04 2020 19:54:21

%S 3,514,1025,1536,19685,20196,20707,39367,39878,59049,262146,262657,

%T 263168,281828,282339,301510,524289,524800,543971,786432,1953127,

%U 1953638,1954149,1972809,1973320,1992491,2215270,2215781,2234952,2477413,3906251,3906762,3925933,4168394,5859375

%N Numbers that are the sum of 3 positive 9th powers.

%H Robert Israel, <a href="/A003392/b003392.txt">Table of n, a(n) for n = 1..10000</a>

%e From _David A. Corneth_, Aug 04 2020: (Start)

%e 391407194198 is in the sequence as 391407194198 = 3^9 + 16^9 + 19^9.

%e 2313193015070 is in the sequence as 2313193015070 = 7^9 + 20^9 + 23^9.

%e 11440294750613 is in the sequence as 11440294750613 = 1^9 + 25^9 + 27^9. (End)

%p N:= 10^10: # For all terms <= N

%p B:= floor(N^(1/9)):

%p S:=select(t -> t <= N, {seq(seq(seq(i^9+j^9+k^9,k=j..B),j=i..B),i=1..B)}):

%p sort(convert(S,list)); # _Robert Israel_, Mar 04 2020

%Y Cf. A001017 (ninth powers).

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_