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A088863
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Number of prime factors of n-th Mersenne number M(p_n).
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4
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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; internal format)
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OFFSET
| 1,5
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COMMENTS
| a(n) = A001222(A001348(n)) = A001222(A000225(A000040(n))
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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
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EXAMPLE
| a(5)=2 because M(p_5)=M(11)=2047 has 2 (not necessarily distinct) prime factors.
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MAPLE
| seq(nops(ifactor(2^ithprime(n)-1)), n=1..32); (Deutsch)
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MATHEMATICA
| Do[m = 2^Prime[n] - 1; Print[Plus @@ Last /@ FactorInteger[m]], {n, 1, 50}] (Propper)
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PROG
| (PARI) for(n=1, 137, print1(bigomega(2^prime(n)-1)", ")) - Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007
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CROSSREFS
| Cf. A046051, A001348.
Sequence in context: A162401 A191090 A097886 * A053283 A035669 A126863
Adjacent sequences: A088860 A088861 A088862 * A088864 A088865 A088866
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KEYWORD
| nonn
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AUTHOR
| Jeppe Stig Nielsen (mail(AT)jeppesn.dk), Nov 25 2003
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EXTENSIONS
| 14 more terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 23 2004
More terms from Ryan Propper (rpropper(AT)stanford.edu), Jul 31 2005
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007
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