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 A259059 #31 Mar 18 2025 21:11:59
%S A259059 227,265,307,353,403,457,515,577,643,713,787,865,947,1033,1123,1217,
%T A259059 1315,1417,1523,1633,1747,1865,1987,2113,2243,2377,2515,2657,2803,
%U A259059 2953,3107,3265,3427,3593,3763,3937,4115,4297,4483,4673,4867,5065,5267,5473
%N A259059 One half of numbers representable in at least two different ways as sums of four distinct nonvanishing squares. See A259058 for these numbers and their representations.
%C A259059 There may be other numbers with this property.
%D A259059 W. Sierpiński, 250 Problems in Elementary Number Theory, American Elsevier Publ. Comp., New York, PWN-Polish Scientific Publishers, Warszawa, 1970, Problem 227, p. 20 and p. 110.
%H A259059 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A259059 a(n) = A259058(n)/2.
%F A259059 a(n) = 2*n^2 + 36*n + 227.
%F A259059 O.g.f.: (227 - 416*x + 193*x^2)/(1-x)^3.
%F A259059 a(n) = 3*a(n-1)-3*a(n-2)+a(n-3). - _Vincenzo Librandi_, Aug 13 2015
%p A259059 A259059:=n->2*n^2 + 36*n + 227: seq(A259059(n), n=0..50); # _Wesley Ivan Hurt_, Aug 13 2015
%t A259059 CoefficientList[Series[(227 - 416 x + 193 x^2)/(1 - x)^3, {x, 0, 50}], x] (* _Vincenzo Librandi_, Aug 13 2015 *)
%o A259059 (Magma) [2*n^2+36*n+227: n in [0..50]]; // _Vincenzo Librandi_, Aug 13 2015
%o A259059 (Magma) I:=[227, 265, 307]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+Self(n-3): n in [1..50]]; // _Vincenzo Librandi_, Aug 13 2015
%o A259059 (PARI) a(n)=2*n^2+36*n+227 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A259059 Cf. A259058.
%K A259059 nonn,easy
%O A259059 0,1
%A A259059 _Wolfdieter Lang_, Aug 12 2015