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Search: id:A088542
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| 2, 3, 7, 71, 179, 547, 983, 1283, 1289, 2909, 3709, 20269, 40829
(list; graph; listen)
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OFFSET
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2,1
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COMMENT
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Also primes n such that the number of prime factors (with repetition) of n! is a multiple of the number of different prime factors of n! (Prime numbers in A088533).
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EXAMPLE
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A022559(7) = 8 is a multiple of A000720(7) = 4.
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MATHEMATICA
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a = {2}; b = {1}; For[n = 3, n < 1000, n++, If[PrimeQ[n], AppendTo[b, 1], c = FactorInteger[n]; For[j = 1, j < Length[c] + 1, j++, b[[PrimePi[c[[j, 1]]]]] = b[[PrimePi[c[[j, 1]]]]] + c[[j, 2]]]]; If[Mod[Plus @@ b, Length[b]] == 0, If[PrimeQ[n], AppendTo[a, n]]]]; a
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PROGRAM
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(PARI) for(x=2, 10000, x1=x!; y=bigomega(x1)/omega(x1); if(y==floor(y), if(isprime(x), print1((x)", "))))
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CROSSREFS
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Cf. A000720, A022559, A088533.
Sequence in context: A057736 A130309 A090870 this_sequence A075840 A096225 A035094
Adjacent sequences: A088539 A088540 A088541 this_sequence A088543 A088544 A088545
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KEYWORD
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hard,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Nov 16 2003
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EXTENSIONS
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Edited and extended by Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 11 2007
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