This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A057904 #29 Jul 07 2025 17:38:56
%S A057904 1,2,4,5,6,7,8,9,11,12,13,14,15,16,18,19,20,21,22,23,25,26,27,28,30,
%T A057904 31,32,33,34,35,37,38,39,40,41,42,44,45,46,47,48,49,50,51,52,53,54,56,
%U A057904 57,58,59,60,61,63,64,65,67,68,69,70,71,72,74,75,76,77,78,79,82,83,84,85,86,87,88
%N A057904 Positive integers that are not the sum of exactly three positive cubes.
%C A057904 Differs from A047318 = numbers not congruent to 3 modulo 7: for example, A047318(26) = 29 is not in this sequence. - _M. F. Hasler_, Jun 30 2025
%H A057904 T. D. Noe, <a href="/A057904/b057904.txt">Table of n, a(n) for n=1..1000</a>
%H A057904 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CubicNumber.html">Cubic Number</a>.
%F A057904 A025456(a(n)) = 0. - _Reinhard Zumkeller_, Apr 23 2009
%e A057904 3 = 1^3 + 1^3 + 1^3, therefore 3 is not in this sequence. Similarly,
%e A057904 10 = 1^3 + 1^3 + 2^3, therefore 10 is not in this sequence.
%t A057904 Select[Range[100], Count[ PowersRepresentations[#, 3, 3], pr_List /; FreeQ[pr, 0]] == 0 &] (* _Jean-François Alcover_, Oct 31 2012 *)
%o A057904 (PARI) select( {is_A057904(n)=n<3 || !for(c=sqrtnint(n\/3,3),sqrtnint(n-2,3), isA003325(n-c^3)&&return)}, [1..99]) \\ _M. F. Hasler_, Jun 30 2025
%Y A057904 Cf. A003072 (complement).
%Y A057904 Cf. A047318 (not congruent to 3 mod 7), A308065 (not the same).
%K A057904 nonn
%O A057904 1,2
%A A057904 _Eric W. Weisstein_