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 A078136 #11 Feb 16 2025 08:32:48 %S A078136 4,8,9,12,13,17,18,21,22,26,27,30,31,35,39 %N A078136 Numbers having exactly one representation as sum of squares>1. %C A078136 A078134(a(n))=1. %C A078136 The sequence is finite with a(15)=39 as last term, since numbers m>39 can be represented as sums of squares>1 (even of squares of primes and even of squares of 2, 3 and 4 and even of squares of 2, 3 and 5) in at least two ways. Proof: if m=40+4k, k>=0, then m=(k+10)*2^2=(k+1)*2^2+4*3^2; if m=41+4k, then m=(k+8)*2^2+3^2=(k+4)*2^2+5^2; if m=42+4k, then m=(k+6)*2^2+2*3^2=(k+2)*2^2+3^2+5^2; if m=43+4k, then m=(k+4)*2^2+3*3^2=k*2^2+2*3^2+5^2. - _Hieronymus Fischer_, Nov 11 2007 %H A078136 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SquareNumber.html">Square Number</a>. %H A078136 <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a> %Y A078136 Cf. A000290, A078137, A078135, A078130. %Y A078136 Cf. A078134, A078139, A090677, A078137, A134754, A134755. %K A078136 nonn,fini,full %O A078136 1,1 %A A078136 _Reinhard Zumkeller_, Nov 19 2002