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 A078138 #23 Feb 16 2025 08:32:48
%S A078138 13,17,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,107,
%T A078138 109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,
%U A078138 199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311
%N A078138 Primes which can be written as sum of squares > 1.
%C A078138 By Sylvester's solution to the Frobenius problem, all integers greater than 4*9 - 4 - 9 = 23 can be represented as a sum of multiples of 4 and 9. Hence all primes except 2,3,5,7,11,19,23 are in this sequence. [_Charles R Greathouse IV_, Apr 19 2010]
%H A078138 Vincenzo Librandi, <a href="/A078138/b078138.txt">Table of n, a(n) for n = 1..1000</a>
%H A078138 J. J. Sylvester, "Question 7382" in <a href="https://archive.org/details/mathematicalque10millgoog">Mathematical Questions from the Educational Times</a>, 37 (1884), p. 26 (search for 7382).
%H A078138 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SumofSquaresFunction.html">Sum of Squares Function</a>
%H A078138 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CoinProblem.html">Coin Problem</a>
%H A078138 <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>
%e A078138 A000040(11) = 31 = 3^2 + 3^2 + 3^2 + 2^2, therefore 31 is a term.
%t A078138 Join[{13,17},Prime[Range[10,100]]] (* _Harvey P. Dale_, May 12 2014 *)
%o A078138 (PARI) a(n)=if(n<3,[13,17][n],prime(n+7))
%Y A078138 Cf. A078134, A078139, A078132.
%K A078138 nonn,easy
%O A078138 1,1
%A A078138 _Reinhard Zumkeller_, Nov 19 2002
%E A078138 Comments, reference, and links by _Charles R Greathouse IV_, Apr 19 2010