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 A066268 #39 Feb 16 2025 08:32:45
%S A066268 1,11,359,75599,174635999,5244319079999,2677277333530799999,
%T A066268 25968760179275365451999999,5793445238736255798985527239999999,
%U A066268 37481813439427687898244906452608585199999999,7517370874372838151564668004911177464757864075999999999
%N A066268 Product of first n primorials - 1.
%H A066268 Harry J. Smith, <a href="/A066268/b066268.txt">Table of n, a(n) for n = 1..37</a>
%H A066268 Romeo Meštrović, <a href="http://arxiv.org/abs/1202.3670">Euclid's theorem on the infinitude of primes: a historical survey of its proofs (300 BC--2012) and another new proof</a>, arXiv preprint arXiv:1202.3670 [math.HO], 2012-2023. - From N. J. A. Sloane, Jun 13 2012
%H A066268 Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_118.htm">Puzzle 118. Primorial product numbers</a>, The Prime Puzzles & Problems Connection.
%H A066268 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Primorial.html">Primorial</a>.
%F A066268 a(n) = A006939(n) - 1. - _Andrew Howroyd_, Dec 10 2024
%e A066268 a(3) = (2)*(2*3)*(2*3*5) - 1 = 359.
%t A066268 Table[Times@@Table[Times@@Prime[Range[n]],{n,k}]-1,{k,40}]
%t A066268 (* or *)
%t A066268 pr2=1; Table[pr1=1; Do[pr1=pr1*Prime[n],{n,k}]; pr2=pr2*pr1; pr2-1,{k,40}] (* _Jayanta Basu_, May 12 2013 *)
%o A066268 (PARI) a(n) = -1 + prod(k=1, n, prime(k)^(n-k+1)) \\ _Andrew Howroyd_, Dec 10 2024
%Y A066268 Cf. A066266, A066267, A066269, A002110, A006939, A006794.
%K A066268 nonn
%O A066268 1,2
%A A066268 _Patrick De Geest_, Dec 16 2001
%E A066268 Offset changed from 0 to 1 by _Harry J. Smith_, Feb 08 2010