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A093429
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Number of distinct prime factors of (p[1]*...*p[n])+(p[n+1]*...*p[2n]), where p[n] is the n-th prime.
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0
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1, 1, 1, 1, 2, 2, 2, 3, 2, 3, 2, 2, 3, 2, 2, 4, 3, 2, 6, 3, 4, 4, 3, 1, 1, 3, 3, 3, 3, 2, 4, 3, 3, 3, 3, 5, 4, 2, 3, 3, 5, 3, 7, 4, 1, 4, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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COMMENTS
| Prime for n=1,2,3,4,24,25,45,59 and no more for n<100.
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LINKS
| Dario Alejandro Alpern, Factorization using the Elliptic Curve Method.
P. Samidoost, Primenumbers group posting.
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EXAMPLE
| a(31)=4 because 509102378439545188849067644696085192959414195658632710736111053092210207
= 3711597629 * 238694867020723 * 226814268663739929299 * 2533557617597929944840907379.
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MATHEMATICA
| PrimeFactors[n_] := Flatten[ Table[ # [[1]], {1} ] & /@ FactorInteger[n]]; f[n_] := Length[ PrimeFactors[ Product[Prime[i], {i, n}] + Product[Prime[i + n], {i, n}]]]; Table[ f[n], {n, 20}]
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CROSSREFS
| Sequence in context: A058013 A031356 A024676 * A089842 A091322 A071215
Adjacent sequences: A093426 A093427 A093428 * A093430 A093431 A093432
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KEYWORD
| nonn
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AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), May 12 2004
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EXTENSIONS
| a(40) - a(48) from Robert G. Wilson v (rgwv(AT)rgwv.com), May 27 2004
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