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 A087046 #39 Feb 16 2025 08:32:50
%S A087046 1,2,12,240,65280,4294901760,18446744069414584320,
%T A087046 340282366920938463444927863358058659840,
%U A087046 115792089237316195423570985008687907852929702298719625575994209400481361428480
%N A087046 Algebraic order of r_n, the value of r in the logistic map that corresponding to the onset of the period 2^n-cycle.
%H A087046 Ilias S. Kotsireas and Kostas Karamanos, <a href="https://doi.org/10.1142/S0218127404010709">Exact computation of the bifurcation point B4 of the logistic map and the Bailey-Broadhurst conjectures</a>, Internat. J. Bifur. Chaos Appl. Sci. Engrg., Vol. 14, No. 7 (2004), pp. 2417-2423; <a href="https://www.researchgate.net/profile/K-Karamanos/publication/263869317_EXACT_COMPUTATION_OF_THE_BIFURCATION_POINT_B4_OF_THE_LOGISTIC_MAP_AND_THE_BAILEY-BROADHURST_CONJECTURES">alternative link</a>.
%H A087046 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LogisticMap.html">Logistic Map</a>.
%F A087046 a(n) = 2^(2^(n - 1)) - 2^(2^(n - 2)) with n>1, a(1)=1. - _Cheng Zhang_, Apr 02 2012
%F A087046 Sum_{n>=1} 1/a(n) = 1 + A346192. - _Amiram Eldar_, Jul 18 2021
%t A087046 Table[If[n <= 1, 1, 2^(2^(n - 1)) - 2^(2^(n - 2))], {n, 1, 10}] (* _Cheng Zhang_, Apr 02 2012 *)
%o A087046 (PARI) a(n) = 1<<(1<<(n-1)) - 1<<(1<<(n-2)); \\ _Kevin Ryde_, Jan 18 2024
%Y A087046 Cf. A086180, A086181, A087089, A118454, A000215, A346192.
%Y A087046 Cf. A051179 (partial sums).
%K A087046 nonn,easy
%O A087046 1,2
%A A087046 _Eric W. Weisstein_, Aug 04 2003
%E A087046 More terms from _Cheng Zhang_, Apr 03 2012