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 A066838 #26 Feb 05 2022 12:37:15
%S A066838 1,1,2,3,6,5,30,105,70,21,210,385,2310,2145,2002,15015,30030,85085,
%T A066838 510510,969969,461890,440895,9699690,37182145,44618574,8580495,
%U A066838 74364290,15935205,223092870,215656441,6469693230,100280245065
%N A066838 Product of primes < n that do not divide n.
%H A066838 Robert Israel, <a href="/A066838/b066838.txt">Table of n, a(n) for n = 1..2350</a>
%F A066838 a(prime(n)) = A002110(n-1). - _Michel Marcus_, May 20 2014
%F A066838 a(n) = e^[Sum_{k=2..n} (1-floor(n/k)+floor((n-1)/k))*A010051(k)*M(k)] where M(n) is the Mangoldt function. - _Anthony Browne_, Jun 17 2016
%e A066838 a(8) = 105 = 3 * 5 * 7 because 3, 5 and 7 are the primes < 8 that do not divide 8.
%p A066838 Primes:= select(isprime, [$2..100]):
%p A066838 seq(convert(select(t -> t <= n and n mod t <> 0, Primes),`*`), n=1..100); # _Robert Israel_, Jun 19 2016
%t A066838 Table[Apply[Times, Select[Prime@ Range@ PrimePi@ n, CoprimeQ[#, n] &] /. {} -> 1], {n, 32}] (* or *)
%t A066838 Table[E^Sum[(1 - Floor[n/k] + Floor[(n - 1)/k]) Boole@ PrimeQ[k] MangoldtLambda@ k, {k, 2, n}], {n, 32}] (* _Michael De Vlieger_, Jun 22 2016 *)
%t A066838 Table[Times@@Complement[Prime[Range[PrimePi[n]]],FactorInteger[n][[All,1]]],{n,40}] (* _Harvey P. Dale_, Feb 05 2022 *)
%o A066838 (PARI) a(n) = prod(i=1, n-1, if (isprime(i) && (n%i) , i, 1)); \\ _Michel Marcus_, May 20 2014
%Y A066838 Cf. A002110 (primorial numbers).
%K A066838 nonn
%O A066838 1,3
%A A066838 _Leroy Quet_, Jan 20 2002