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 A088863 Number of prime factors of n-th Mersenne number M(p_n). 6
 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, 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, 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 COMMENTS a(n) = A001222(A001348(n)) = A001222(A000225(A000040(n)). LINKS Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007, Table of n, a(n) for n = 1..137 Herman Jamke, The first 137 terms in detail EXAMPLE a(5)=2 because M(p_5)=M(11)=2047 has 2 (not necessarily distinct) prime factors. MAPLE seq(nops(ifactor(2^ithprime(n)-1)), n=1..32); # Emeric Deutsch, Dec 23 2004 MATHEMATICA Do[m = 2^Prime[n] - 1; Print[Plus @@ Last /@ FactorInteger[m]], {n, 1, 50}] (* Ryan Propper, Jul 31 2005 *) PROG (PARI) for(n=1, 137, print1(bigomega(2^prime(n)-1)", ")) \\ Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007 CROSSREFS Cf. A046051, A001348. Sequence in context: A097886 A308293 A249298 * A053283 A035669 A126863 Adjacent sequences:  A088860 A088861 A088862 * A088864 A088865 A088866 KEYWORD nonn AUTHOR Jeppe Stig Nielsen, Nov 25 2003 EXTENSIONS 14 more terms from Emeric Deutsch, Dec 23 2004 More terms from Ryan Propper, Jul 31 2005 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007 STATUS approved

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Last modified April 13 19:42 EDT 2021. Contains 342941 sequences. (Running on oeis4.)