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 A006281 M2260 #26 Jul 08 2025 16:45:46 %S A006281 0,3,2,18,98,33282,319994402,354455304050635218, %T A006281 36294953231792713902640647988908098 %N A006281 Partial quotients in continued fraction expansion of 2C-1, where C is Cahen's constant. %D A006281 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006281 Amiram Eldar, <a href="/A006281/b006281.txt">Table of n, a(n) for n = 0..12</a> %H A006281 J. L. Davison and Jeffrey O. Shallit, <a href="https://doi.org/10.1007/BF01332350">Continued Fractions for Some Alternating Series</a>, Monatshefte für Mathematik, Vol. 111 (1991), pp. 119-126; <a href="http://gdz.sub.uni-goettingen.de/dms/load/img/?PPN=PPN362162050_0111&DMDID=DMDLOG_0013&LOGID=LOG_0013&PHYSID=PHYS_0126">alternative link</a>. %t A006281 s[0] = 2; s[n_] := s[n] = s[n - 1]^2 - s[n-1] + 1; h[0] = 1; h[n_] := h[n] = (s[n] - 1)/(2*h[n-1]); a[0] = 0; a[1] = 3; a[n_] := 2*h[n-1]^2; Array[a, 9, 0] (* _Amiram Eldar_, Mar 19 2024 *) %Y A006281 Cf. A006279, A006280, A118227. %K A006281 nonn,easy %O A006281 0,2 %A A006281 _N. J. A. Sloane_