A004833 - OEIS

%I #21 Aug 05 2020 15:48:39

%S 0,1,2,3,4,16,17,18,19,32,33,34,48,49,64,81,82,83,84,97,98,99,113,114,

%T 129,162,163,164,178,179,194,243,244,256,257,258,259,272,273,274,288,

%U 289,304,324,337,338,339,353,354,369,418,419,434,499,512,513,514,528,529,544,593,594,609,625,626,627,628,641,642,643

%N Numbers that are the sum of at most 4 nonzero 4th powers.

%H Alois P. Heinz, <a href="/A004833/b004833.txt">Table of n, a(n) for n = 1..20000</a> (first 1000 terms from T. D. Noe)

%t Reap[For[n = 0, n < 1000, n++, If[MatchQ[ PowersRepresentations[n, 4, 4], {{_, _, _, _}, ___}], Print[n]; Sow[n]]]][[2, 1]] (* _Jean-François Alcover_, Oct 30 2017 *)

%o (PARI) N=1000; x='x+O('x^N); /* terms up to N-1 */

%o S=ceil(N^(1/4));

%o v=Vec(sum(k=-S,S,x^(k^4))^4);

%o for(n=1,#v,if(v[n]!=0,print1(n-1,", "))); /* Joerg Arndt, Jun 25 2011 */

%Y Column k=4 of A336820.

%K nonn

%O 1,3

%A _N. J. A. Sloane_