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 A088863 #25 Aug 25 2024 09:57:37
%S A088863 1,1,1,1,2,1,1,1,2,3,1,2,2,3,3,3,2,1,2,3,3,3,2,1,2,2,2,1,2,5,1,2,2,2,
%T A088863 2,5,4,5,2,4,3,4,5,3,2,2,3,6,2,4,4,6,2,5,3,4,2,2,3,2,3,2,5,3,4,4,3,5,
%U A088863 2,3,3,6,5,2,2,5,3,9,4,3,5,2,8,4,4,3,5,2,4,6,3,4,2,7,3,4,4,1,2,5,4,5,3,5,4
%N A088863 Number of prime factors of n-th Mersenne number M(p_n).
%H A088863 Max Alekseyev, <a href="/A088863/b088863.txt">Table of n, a(n) for n = 1..197</a> (first 137 terms from Herman Jamke)
%H A088863 Herman Jamke, <a href="/A088863/a088863.txt">The first 137 terms in detail</a>
%F A088863 a(n) = A001222(A001348(n)) = A001222(A000225(A000040(n))).
%e A088863 a(5)=2 because M(p_5)=M(11)=2047 has 2 (not necessarily distinct) prime factors.
%p A088863 seq(nops(ifactor(2^ithprime(n)-1)),n=1..32); # _Emeric Deutsch_, Dec 23 2004
%t A088863 Do[m = 2^Prime[n] - 1; Print[Plus @@ Last /@ FactorInteger[m]], {n, 1, 50}] (* _Ryan Propper_, Jul 31 2005 *)
%o A088863 (PARI) for(n=1,137,print1(bigomega(2^prime(n)-1)",")) \\ Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007
%Y A088863 Cf. A001348, A003260, A046051, A046932.
%K A088863 nonn
%O A088863 1,5
%A A088863 _Jeppe Stig Nielsen_, Nov 25 2003
%E A088863 14 more terms from _Emeric Deutsch_, Dec 23 2004
%E A088863 More terms from _Ryan Propper_, Jul 31 2005
%E A088863 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007