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A103767
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Numbers n such that prime(n)*prime(n+1)*prime(n+2) - 1 is semiprime.
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0
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6, 10, 29, 42, 44, 55, 57, 102, 104, 111, 120, 136, 174, 184, 257, 269, 308, 325, 327, 401, 426, 504, 514, 565, 571, 594, 595, 652, 717, 755, 864, 882, 901, 907, 985, 1014, 1074, 1134, 1141, 1156, 1198, 1301, 1327, 1346, 1362, 1654, 1670, 1674, 1778, 1897
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| prime(10)*prime(11)*prime(12) - 1 = 29*31*37 - 1 = 33262= 2*16631, hence 10 is
a term.
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PROG
| (PARI) for(n=1, 1900, if(bigomega(prime(n)*prime(n+1)*prime(n+2)-1)==2, print1(n, ", ")))
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CROSSREFS
| Cf. A001358, A006881, A103614, A103746.
Sequence in context: A014494 A129545 A097578 * A025129 A093559 A163478
Adjacent sequences: A103764 A103765 A103766 * A103768 A103769 A103770
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KEYWORD
| nonn,easy
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AUTHOR
| Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Mar 29 2005
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