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 A054990 #25 Mar 06 2022 22:52:18
%S A054990 1,1,1,2,2,2,2,2,3,2,1,3,2,2,3,5,3,6,2,2,3,3,4,2,2,2,1,2,3,5,4,4,5,2,
%T A054990 5,6,1,2,4,7,1,3,4,3,3,3,4,2,5,5,6,4,4,2,2,4,3,4,2,4,4,3,5,3,4,5,4,5,
%U A054990 6,5,2,7,1,4,2,3,1,6,3,4,7,3,3,3,5,5,4,3,8,3,6,2,4,3,4,5,6,6,5,5,4,5
%N A054990 Number of prime divisors of n! + 1 (counted with multiplicity).
%C A054990 The smallest k! with n prime factors occurs for n in A060250.
%C A054990 103!+1 = 27437*31084943*C153, so a(103) is unknown until this 153-digit composite is factored. a(104) = 4 and a(105) = 6. - _Rick L. Shepherd_, Jun 10 2003
%H A054990 Amiram Eldar, <a href="/A054990/b054990.txt">Table of n, a(n) for n = 1..139</a>
%H A054990 Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha103.htm">Factorizations of many number sequences</a>
%H A054990 Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha104.htm">Factorizations of many number sequences</a>
%H A054990 R. G. Wilson v, <a href="/A038507/a038507.txt">Explicit factorizations</a>
%H A054990 Paul Leyland, <a href="http://www.leyland.vispa.com/numth/factorization/factors/factorial+">Factors of n!+1</a>.
%e A054990 a(2)=2 because 4! + 1 = 25 = 5*5
%t A054990 a[q_] := Module[{x, n}, x=FactorInteger[q!+1]; n=Length[x]; Sum[Table[x[[i]][[2]], {i, n}][[j]], {j, n}]]
%t A054990 A054990[n_Integer] := PrimeOmega[n! + 1]; Table[A054990[n], {n,100}] (* _Vladimir Joseph Stephan Orlovsky_, Jul 22 2011 *)
%o A054990 (PARI) for(n=1,64,print1(bigomega(n!+1),","))
%Y A054990 Cf. A000040 (prime numbers), A001359 (twin primes).
%Y A054990 Cf. A038507, A054988, A054989, A054991, A054992.
%Y A054990 Cf. A066856 (number of distinct prime divisors of n!+1), A084846 (mu(n!+1)).
%K A054990 nonn,hard
%O A054990 1,4
%A A054990 Arne Ring (arne.ring(AT)epost.de), May 30 2000
%E A054990 More terms from _Robert G. Wilson v_, Mar 23 2001
%E A054990 More terms from _Rick L. Shepherd_, Jun 10 2003