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 A067420 #11 Jun 29 2023 10:44:28 %S A067420 1,7,105,1575,23625,354375,5315625,79734375,1196015625,17940234375, %T A067420 269103515625,4036552734375,60548291015625,908224365234375, %U A067420 13623365478515625,204350482177734375,3065257232666015625 %N A067420 Fifth column of triangle A067417. %H A067420 Vincenzo Librandi, <a href="/A067420/b067420.txt">Table of n, a(n) for n = 0..800</a> %H A067420 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (15). %F A067420 a(n) = A067417(n+4, 4). %F A067420 a(n) = 7*(3*5)^(n-1), n >= 1, a(0)=1. %F A067420 G.f.: (1-8*x)/(1-15*x). %o A067420 (Magma) [Ceiling(7*(3*5)^(n-1)): n in [0..20]]; // _Vincenzo Librandi_, Oct 02 2011 %Y A067420 Cf. A067419 (fourth column), A067421 (sixth column), A001024 (powers of 15). %K A067420 nonn,easy %O A067420 0,2 %A A067420 _Wolfdieter Lang_, Jan 25 2002