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 A195503 #37 Aug 19 2025 20:54:11 %S A195503 4,15,56,209,780,2911,10864,40545,151316,564719,2107560,7865521, %T A195503 29354524,109552575,408855776,1525870529,5694626340,21252634831, %U A195503 79315912984,296011017105,1104728155436,4122901604639,15386878263120,57424611447841 %N A195503 Numerators b(n) of Pythagorean approximations b(n)/a(n) to sqrt(3). %C A195503 See A195500 for discussion and list of related sequences; see A195499 for Mathematica program. %C A195503 Essentially the same as A001353, A106707, A125905 and likely also A010905. - _R. J. Mathar_, Sep 21 2011 %C A195503 If started 1, 4, 15, 56, ...., denominators a(n) of Pythagorean approximations b(n)/a(n) to sqrt(1/3). - _Clark Kimberling_, Sep 22 2011 %H A195503 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (4,-1). %F A195503 a(n) = A001353(n+1). - _R. J. Mathar_, Sep 21 2011 %F A195503 Empirical g.f.: x*(4-x)/(1-4*x+x^2). - _Colin Barker_, Jan 04 2012 %Y A195503 Cf. A195500, A195499, A195531. %K A195503 nonn,easy %O A195503 1,1 %A A195503 _Clark Kimberling_, Sep 20 2011