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 A257273 #21 Dec 21 2024 12:28:45
%S A257273 2,5,14,44,152,560,2144,8384,33152,131840,525824,2100224,8394752,
%T A257273 33566720,134242304,536920064,2147581952,8590131200,34360131584,
%U A257273 137439739904,549757386752,2199026401280,8796099313664,35184384671744,140737513521152,562950003752960,2251799914348544,9007199456067584
%N A257273 a(n) = 2^(n-1)*(2^n+3).
%C A257273 a(n) is in A125246 <=> n is in A057732 <=> A062709(n) is in A057733.
%C A257273 These are also the row sum of the triangle A146769: For n>=1, a(n-1) is the sum of row n of A146769.
%H A257273 Colin Barker, <a href="/A257273/b257273.txt">Table of n, a(n) for n = 0..1000</a>
%H A257273 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (6,-8).
%F A257273 G.f.: (2-7*x)/((1-4*x)*(1-2*x)). - _Vincenzo Librandi_, Apr 27 2015
%F A257273 a(n) = 6*a(n-1)-8*a(n-2). - _Colin Barker_, Apr 27 2015
%t A257273 Table[2^(n - 1) (2^n + 3), {n, 0, 30}] (* _Bruno Berselli_, Apr 27 2015 *)
%t A257273 CoefficientList[Series[(2 - 7 x)/((1 - 4 x) (1 - 2 x)), {x, 0, 30}], x] (* _Vincenzo Librandi_, Apr 27 2015 *)
%t A257273 LinearRecurrence[{6,-8},{2,5},30] (* _Harvey P. Dale_, Dec 21 2024 *)
%o A257273 (PARI) a(n)=2^(n-1)*(2^n+3)
%o A257273 (Magma) [2^(n-1)*(2^n+3): n in [0..35]]; // _Vincenzo Librandi_, Apr 27 2015
%o A257273 (PARI) Vec((2-7*x)/((1-4*x)*(1-2*x)) + O(x^100)) \\ _Colin Barker_, Apr 27 2015
%Y A257273 Cf. A000079, A007582, A028403, A256873, A256871, A257272.
%Y A257273 Cf. A062709, A057732, A057733.
%K A257273 nonn,easy
%O A257273 0,1
%A A257273 _M. F. Hasler_, Apr 27 2015