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 A061720 #18 Feb 23 2022 12:24:33
%S A061720 1,4,24,180,2100,27720,480480,9189180,213393180,6246600360,
%T A061720 194090796900,7220177644680,296829525392400,12778511068142820,
%U A061720 601807021256821380,31974268694601553320,1890171191677022594340,115365621009252758344200,7741033169720860084895820
%N A061720 First differences of sequence of primorials.
%C A061720 Largest number below primorial(n + 1) to be divisible by the first n primes. - _Alonso del Arte_, Dec 13 2014
%H A061720 Harry J. Smith, <a href="/A061720/b061720.txt">Table of n, a(n) for n=0..100</a>
%H A061720 <a href="/index/Pri#primorial_numbers">Index entries for sequences related to primorial numbers</a>
%F A061720 a(n) = A002110(n+1) - A002110(n) = A002110(n)*A006093(n+1).
%e A061720 a(2) = primorial(3) - primorial(2) = 30 - 6 = 24.
%e A061720 a(3) = primorial(4) - primorial(3) = 210 - 30 = 180.
%p A061720 p:= proc(n) option remember; `if`(n=0, 1, ithprime(n)*p(n-1)) end:
%p A061720 a:= n-> p(n+1)-p(n):
%p A061720 seq(a(n), n=0..20); # _Alois P. Heinz_, Feb 23 2022
%t A061720 Differences[FoldList[Times, 1, Prime[Range[20]]]] (* _Alonso del Arte_, Dec 13 2014 *)
%o A061720 (PARI) { n=-1; r=q=1; forprime (p=2, prime(101), r*=p; write("b061720.txt", n++, " ", r-q); q=r ) } \\ _Harry J. Smith_, Jul 27 2009
%Y A061720 Cf. A002110, A006093, A286629.
%Y A061720 Subsequence of A276155.
%K A061720 easy,nonn
%O A061720 0,2
%A A061720 _Labos Elemer_, Jun 20 2001
%E A061720 Since primorial(0) = 1, term a(0) = 1 added by _Harry J. Smith_, Jul 27 2009