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Search: id:A128994
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| A128994 |
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First of three consecutive pairwise coprime numbers such that the product of any two plus the third is a prime. |
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+0
1
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| 1, 2, 3, 5, 6, 8, 19, 25, 32, 38, 53, 84, 110, 114, 119, 122, 125, 129, 133, 159, 170, 175, 229, 235, 263, 302, 313, 320, 385, 419, 489, 495, 543, 572, 593, 643, 749, 786, 815, 866, 929, 949, 966, 1122, 1123, 1173, 1254, 1365, 1459, 1470, 1508, 1542, 1565, 1584
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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For 6 the next two numbers such that all are pairwise coprime are 7 and 11.
All three numbers 6*7+11, 6*11+7, 7*11+6 are prime, therefore 6 is in the sequence.
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MATHEMATICA
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l = {}; For[n = 1, n < 2000, n++, a = n; i = 1; While[Not[GCD[a, a + i]], i++ ]; b = a + i; i = 1; While[Not[GCD[a, b + i] == 1 && GCD[b, b + i] == 1], i++ ]; c = b + i; If[PrimeQ[a*b + c] && PrimeQ[a*c + b] && PrimeQ[b*c + a], AppendTo[l, n]]]; l
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CROSSREFS
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Sequence in context: A139443 A088497 A088485 this_sequence A098211 A073673 A118809
Adjacent sequences: A128991 A128992 A128993 this_sequence A128995 A128996 A128997
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KEYWORD
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nonn
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AUTHOR
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J. M. Bergot (thekingfishb(AT)yahoo.ca), Apr 30 2007
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EXTENSIONS
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Edited and extended by Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Aug 07 2007
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