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Search: id:A077287
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| A077287 |
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Unique encountered factors from ( (prime(n)*prime(n+1))^2 + 1 )/2. |
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+0
1
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| 113, 613, 5, 24421, 101, 2042221, 13, 41, 60731221, 102975601, 6653, 253102501, 327449641, 17, 14957, 722798221, 37, 35597, 797, 233, 2284271641, 7937, 337, 73, 29, 53, 46414646521, 57358506301, 2521, 89, 89249322541, 61, 281, 56597
(list; graph; listen)
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OFFSET
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2,1
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COMMENT
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The sequence only looks at the first prime factors when several are encountered. Duplicates have been removed.
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REFERENCES
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C. Stanley Ogilvy and John T. Anderson, Excursions in Number Theory. Dover. New York: 1988.
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LINKS
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Chris Nash, PrimeForm - Probable Prime and Classical Primality Testing for 32-bit Windows.
George F. Woltman, GIMPS - The Great Internet Mersenne Prime Search.
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EXAMPLE
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Primeform reports 2281 as the factor from ( (P(38321)*P(38322))2+1)/2; this is M17.
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MATHEMATICA
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PrimeFactors[n_] := Flatten[ Table[ # [[1]], {1}] & /@ FactorInteger[n]]; a = {}; Do[l = PrimeFactors[((Prime[n]*Prime[n + 1])^2 + 1)/2]; If[ Position[a, l[[1]]] == {}, AppendTo[a, l[[1]]]], {n, 2, 127}]; a
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CROSSREFS
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Sequence in context: A118506 A109563 A142024 this_sequence A087294 A152928 A075030
Adjacent sequences: A077284 A077285 A077286 this_sequence A077288 A077289 A077290
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KEYWORD
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nonn
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AUTHOR
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Bill R McEachen (bmceache(AT)centralsan.dst.ca.us), Aug 22 2003
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EXTENSIONS
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Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Sept 27 2003
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