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 A004435 #21 Oct 26 2023 00:19:23 %S A004435 2,3,6,7,8,11,12,14,15,18,19,21,22,23,24,27,28,30,31,32,33,35,38,39, %T A004435 42,43,44,46,47,48,51,54,55,56,57,59,60,62,63,66,67,69,70,71,72,75,76, %U A004435 77,78,79,83,84,86,87,88,91 %N A004435 Positive integers that are not the sum of 2 distinct square integers. %C A004435 A025435(a(n)) = 0. - _Reinhard Zumkeller_, Dec 20 2013 %H A004435 T. D. Noe, <a href="/A004435/b004435.txt">Table of n, a(n) for n=1..1000</a> %H A004435 <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a> %t A004435 Select[Range[100], Reduce[0 <= i < j && # == i^2 + j^2, {i, j}, Integers] === False &] (* _Jean-François Alcover_, Aug 01 2018 *) %o A004435 (Haskell) %o A004435 a004435 n = a004435_list !! (n-1) %o A004435 a004435_list = [x | x <- [1..], a025435 x == 0] %o A004435 -- _Reinhard Zumkeller_, Dec 20 2013 %Y A004435 Cf. A001983 (complement). %K A004435 nonn %O A004435 1,1 %A A004435 _N. J. A. Sloane_