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 A205646 #31 Nov 09 2023 11:05:54 %S A205646 17,19,25,43,97,259,745,2203,6577,19699,59065,177163,531457,1594339, %T A205646 4782985,14348923,43046737,129140179,387420505,1162261483,3486784417, %U A205646 10460353219,31381059625,94143178843,282429536497,847288609459,2541865828345,7625597485003 %N A205646 Number of empty faces in Freij's family of Hansen polytopes. %C A205646 Freij's study produces a new family of Hansen polytopes that have only 3^d+16 nonempty faces. %H A205646 Paolo Xausa, <a href="/A205646/b205646.txt">Table of n, a(n) for n = 0..1000</a> %H A205646 Ragnar Freij, Matthias Henze, Moritz W. Schmitt, and Günter M. Ziegler, <a href="http://arxiv.org/abs/1201.5790">Face numbers of centrally symmetric polytopes from split graphs</a>, arXiv:1201.5790 [math.MG], 2012. %H A205646 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (4,-3). %F A205646 a(n) = 3^n + 16. %F A205646 a(n) = 4*a(n-1) - 3*a(n-2). G.f.: (17 - 49*x) / ((1 - x)*(1 - 3*x)). - _Colin Barker_, May 02 2013 %F A205646 From _Elmo R. Oliveira_, Nov 09 2023: (Start) %F A205646 a(n) = 3*a(n-1) - 32 with a(0) = 17. %F A205646 E.g.f.: exp(3*x) + 16*exp(x). (End) %e A205646 a(4) = (3^4) + 16 = 97. %t A205646 3^Range[0,30]+16 (* _Paolo Xausa_, Oct 24 2023 *) %Y A205646 Cf. A000244 (powers of 3), A205647. %K A205646 nonn,easy %O A205646 0,1 %A A205646 _Jonathan Vos Post_, Jan 29 2012 %E A205646 Terms corrected by _Colin Barker_, May 02 2013