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 A103893 #26 Jan 21 2024 02:22:58
%S A103893 1,1,1,1,2,3,3,4,2,3,2,4,4,5,3,2,3,4,6,5,5,5,5,6,5,4,5,3,7,5,5,8,5
%N A103893 Number of distinct prime factors of prime(n)! / prime(n)# + 1.
%C A103893 Also the number of distinct prime factors of the P_n-th compositorial.
%C A103893 a(31) > 4 and its composite part is a 155-digit number.
%C A103893 a(34) >= 4. - _Amiram Eldar_, Jan 21 2024
%H A103893 Dario Alejandro Alpern, <a href="https://www.alpertron.com.ar/ECM.HTM">Factorization using the Elliptic Curve Method</a>.
%H A103893 Factordb.com, <a href="http://factordb.com/index.php?query=139%21%2F139%23%2B1">Status of 139!/139#+1</a>.
%H A103893 Hisanori Mishimar, <a href="https://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/compo_p.htm">Compositorial + 1 (n = 4 to 150)</a>.
%H A103893 Reinhard Zumkeller, <a href="/A103890/a103890.txt">prime(n)!/prime(n)#+1</a>.
%F A103893 a(n) = A001221(A103890(n)).
%t A103893 bigomega[n_Integer] := Plus @@ Last /@ FactorInteger[n]; f[n_] := Prime[n]!/Product[Prime[i], {i, n}] + 1; Table[ f[n], {n, 27}] (* _Robert G. Wilson v_, Mar 11 2005 *)
%Y A103893 Cf. A001221, A103858, A103890.
%K A103893 nonn,more
%O A103893 1,5
%A A103893 _Reinhard Zumkeller_, Feb 20 2005
%E A103893 Corrected and extended by _Robert G. Wilson v_, Mar 12 2005
%E A103893 a(31)-a(33) using factordb.com added by _Amiram Eldar_, Jan 21 2024