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 A274073 #10 Jun 09 2016 12:03:14 %S A274073 0,7,35,217,1295,7777,46655,279937,1679615,10077697,60466175, %T A274073 362797057,2176782335,13060694017,78364164095,470184984577, %U A274073 2821109907455,16926659444737,101559956668415,609359740010497,3656158440062975,21936950640377857,131621703842267135 %N A274073 a(n) = 6^n-(-1)^n. %H A274073 Colin Barker, <a href="/A274073/b274073.txt">Table of n, a(n) for n = 0..1000</a> %H A274073 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (5,6). %F A274073 O.g.f.: 7*x/((1+x)*(1-6*x)). %F A274073 E.g.f.: exp(6*x) - exp(-x). %F A274073 a(n) = 5*a(n-1) + 6*a(n-2) for n>1. %F A274073 a(n) = 7*A015540(n). %o A274073 (PARI) concat(0, Vec(7*x/((1+x)*(1-6*x)) + O(x^30))) %Y A274073 Cf. A015540. %Y A274073 Sequences of the type k^n-(-1)^n: A062157 (k=0), A010673 (k=1), A062510 (k=2), A105723 (k=3), A247281 (k=4), A274072 (k=5), this sequence (k=6). %K A274073 nonn,easy %O A274073 0,2 %A A274073 _Colin Barker_, Jun 09 2016