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 A178427 #19 May 23 2024 16:23:36
%S A178427 7,9,65,4097,16777217,281474976710657,79228162514264337593543950337,
%T A178427 6277101735386680763835789423207666416102355444464034512897
%N A178427 7 followed by the Fermat numbers A152581.
%C A178427 If a(0)=3, the recursion formula gives A000215.
%F A178427 a(0)=7. a(n) = 2 + Product_{i=0..n-1} a(i).
%t A178427 a[0] := 7;
%t A178427 a[n_] := a[n] = Product[a[i], {i, 0, n - 1}] + 2;
%t A178427 Table[a[n], {n, 0, 10}]
%Y A178427 Cf. A000215, A152581, A178426, A178428.
%K A178427 nonn,less
%O A178427 0,1
%A A178427 _Roger L. Bagula_, May 27 2010
%E A178427 Definition simplified by the Assoc. Eds. of the OEIS - May 28 2010
%E A178427 Incorrect a(8) removed by _Georg Fischer_, May 22 2024