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 A307685 #16 Jun 15 2025 23:57:53 %S A307685 1,3,6,17,48,143,426,1277,3828,11483,34446,103337,310008,930023, %T A307685 2790066,8370197,25110588,75331763,225995286,677985857,2033957568, %U A307685 6101872703,18305618106,54916854317,164750562948,494251688843,1482755066526,4448265199577,13344795598728,40034386796183 %N A307685 Clique covering number of the n-Sierpinski gasket graph. %H A307685 Andrew Howroyd, <a href="/A307685/b307685.txt">Table of n, a(n) for n = 1..1000</a> %H A307685 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CliqueCoveringNumber.html">Clique Covering Number</a>. %H A307685 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SierpinskiGasketGraph.html">Sierpinski Gasket Graph</a>. %H A307685 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,1,-3). %F A307685 a(n) = (7*3^(n-2) + (-1)^n + 4)/4 for n > 1. - _Andrew Howroyd_, May 30 2025 %o A307685 (PARI) a(n) = if(n==1, 1, (7*3^(n-2) + (-1)^n + 4)/4) \\ _Andrew Howroyd_, May 30 2025 %Y A307685 Cf. A307702. %K A307685 nonn,easy %O A307685 1,2 %A A307685 _Eric W. Weisstein_, Apr 21 2019 %E A307685 a(9) onwards from _Andrew Howroyd_, May 30 2025