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 A262352 #19 Nov 06 2018 21:18:46
%S A262352 0,-1,0,-1,0,-1,0,-1,0,-1,0,-1,0,-1,0,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,
%T A262352 -1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,
%U A262352 1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-2,1,-2,1,-2,1,-2,1,-2,1,-2,1,-2,1,-2,1
%N A262352 a(n) = Sum_{k=0..n} (-1)^k*floor(k^(1/4)).
%H A262352 Antti Karttunen, <a href="/A262352/b262352.txt">Table of n, a(n) for n = 0..16383</a>
%H A262352 Antti Karttunen, <a href="/A262352/a262352.txt">Data supplement: n, a(n) computed for n = 0..65537</a>
%F A262352 a(n) = floor(n^(1/4))*(-1)^n/2-((-1)^(floor(n^(1/4))+1)+1)/4.
%e A262352 Letting [] denote the floor function, a(7) = [0^(1/4)] - [1^(1/4)] + [2^(1/4)] - [3^(1/4)] + [4^(1/4)] - [5^(1/4)] + [6^(1/4)] - [7^(1/4)] = 0 - 1 + 1 - 1 + 1 - 1 + 1 - 1 = -1.
%t A262352 Print[Table[Sum[(-1)^k*Floor[k^(1/4)],{k,0,n}],{n,0,100}]] ;
%o A262352 (PARI) a(n)=floor(n^(1/4))*(-1)^n/2-((-1)^(floor(n^(1/4))+1)+1)/4
%o A262352 (PARI) a(n)=sum(k=0,n,(-1)^k*floor(k^(1/4)))
%o A262352 (PARI) A262352(n) = sum(k=0,n,((-1)^k)*sqrtnint(k, 4)); \\ _Antti Karttunen_, Nov 06 2018
%Y A262352 Cf. A270370, A268173, A022554, A031876, A032512, A032513, A032514, A032515, A032516, A032517, A032518, A032519, A032520, A032521.
%K A262352 sign,easy
%O A262352 0,82
%A A262352 _John M. Campbell_, Mar 24 2016
%E A262352 More terms from _Antti Karttunen_, Nov 06 2018