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 A133678 #12 Jan 02 2024 08:56:27
%S A133678 1,6,72,684,7128,71496,728352,7372944,74828448,758634336,7694600832,
%T A133678 78030247104,791354717568,8025398683776,81389290240512,
%U A133678 825402486161664,8370765107071488,84891495061218816,860921104864315392,8730969421757082624,88544502934843742208
%N A133678 a(n)=6*a(n-1)+42*a(n-2) for n>=3, a(0)=1, a(1)=6, a(2)=72 .
%D A133678 D. A. Cox, Primes of the form x^2+ny^2, Wiley, New York, 1989.
%D A133678 D. E. Flath, Introduction to Number Theory, Wiley-Interscience, 1989.
%H A133678 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (6,42).
%F A133678 G.f.: (1-6*x^2)/(1-6*x-42*x^2) . a(n) = Sum_{k, 0<=k<=n}A122950(n,k)*6^k .
%F A133678 a(1)=6, a(2)=72, a(n)=6*a(n-1)+42*a (n-2). - _Harvey P. Dale_, Mar 25 2015
%t A133678 Join[{1},LinearRecurrence[{6,42},{6,72},20]] (* _Harvey P. Dale_, Mar 25 2015 *)
%K A133678 easy,nonn
%O A133678 0,2
%A A133678 _Philippe Deléham_, Dec 31 2007
%E A133678 Corrected and extended by _Harvey P. Dale_, Mar 25 2015