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 A307457 #14 Jun 13 2025 12:40:45 %S A307457 3,6,14,30,62,126,254,510,1022,2046,4094,8190,16382,32766,65534, %T A307457 131070,262142,524286,1048574,2097150,4194302,8388606,16777214, %U A307457 33554430,67108862,134217726,268435454,536870910,1073741822,2147483646,4294967294,8589934590 %N A307457 Longest path length in the n-Apollonian network. %H A307457 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ApollonianNetwork.html">Apollonian Network</a>. %H A307457 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LongestPath.html">Longest Path</a>. %H A307457 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2). %F A307457 a(n) = 2^(n+1) - 2 = A000918(n+1) for n > 1. - _Andrew Howroyd_, Jun 09 2025 %Y A307457 Essentially the same as A000918 shifted, and A095121. %Y A307457 Cf. A307549. %K A307457 nonn,easy %O A307457 1,1 %A A307457 _Eric W. Weisstein_, Apr 08 2019 %E A307457 a(5) onwards from _Andrew Howroyd_, Jun 09 2025