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 A308819 #15 Apr 24 2025 08:49:54
%S A308819 1,1,2,6,24,120,120,840,6720,60480,60480,665280,665280,8648640,
%T A308819 8648640,8648640,138378240,2352430080,2352430080,44696171520,
%U A308819 44696171520,44696171520,44696171520,1028011944960,1028011944960,25700298624000,25700298624000,693908062848000
%N A308819 Product of prime powers <= n.
%C A308819 a(n) is the smallest number that's divisible by all numbers less than or equal to n. - _Keith F. Lynch_, Apr 24 2025
%e A308819 a(9) = 60480 because 2, 3, 4, 5, 7, 8, 9 are the prime powers less than or equal to 9 and 2 * 3 * 4 * 5 * 7 * 8 * 9 = 60480.
%t A308819 a[n_] := Product[If[PrimePowerQ[k], k, 1], {k, 1, n}]; Table[a[n], {n, 0, 27}]
%t A308819 Module[{nn=50,ppwr},ppwr=Select[Range[nn],PrimePowerQ[#]&];Table[Times@@ Select[ ppwr,#<= n&],{n,0,nn}]] (* _Harvey P. Dale_, Apr 03 2024 *)
%o A308819 (PARI) a(n) = prod(k=1, n, if (isprime(k) || isprimepower(k), k, 1)); \\ _Michel Marcus_, Jun 27 2019
%Y A308819 Cf. A000961, A024923, A034386, A065515, A074793, A100994, A179215, A246655.
%K A308819 nonn
%O A308819 0,3
%A A308819 _Ilya Gutkovskiy_, Jun 26 2019