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 A145543 #19 Feb 26 2020 15:51:40 %S A145543 1,4,9,31,71,244,559,1921,4401,15124,34649,119071,272791,937444, %T A145543 2147679,7380481,16908641,58106404,133121449,457470751,1048062951, %U A145543 3601659604,8251382159,28355806081,64962994321,223244789044,511452572409,1757602506271,4026657584951 %N A145543 Denominators in continued fraction expansion of sqrt(3/5). %C A145543 A145542/a(n) tends to sqrt(3/5). %F A145543 Use the partial quotients of the continued fraction expansion of sqrt(3/5) as recursive operation multipliers, given a(1) = 1, a(2) = 4. %F A145543 Empirical G.f.: x*(1+4*x+x^2-x^3)/(1-8*x^2+x^4). - _Colin Barker_, Jan 04 2012 %e A145543 Since the partial quotients of CF sqrt(3/5)= [1, 3, 2, 3, 2, 3,...] denominators are 1, 4, 9, 31, 71, 244, 559,...; given a(1) = 1, a(2) = 4. %t A145543 Rest @ Denominator @ Convergents [Sqrt[3/5], 30] (* _Amiram Eldar_, Feb 26 2020 *) %Y A145543 Cf. A145542. %K A145543 nonn,easy %O A145543 1,2 %A A145543 _Gary W. Adamson_, Oct 12 2008 %E A145543 More terms from _Amiram Eldar_, Feb 26 2020