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Search: id:A154728
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| A154728 |
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Products of three consecutive primes of the form 6n+1 (see A002476). |
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+0
4
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| 1729, 7657, 21793, 49321, 97051, 175741, 298351, 386389, 559399, 789289, 1089019, 1425829, 1924177, 2665603, 3295273, 3864241, 4631971, 5694079, 6951667, 8103877, 9363547, 10775137, 12307147, 14956219, 18091147, 21243961, 24066037
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Note that a(1)=1729 is the Hardy-Ramanujan number (See taxicab numbers in A001235, A011541).
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EXAMPLE
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13, 19, 31 are three consecutive primes of the form 6n+1 and 13*19*31=7657. [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 21 2009]
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MAPLE
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a := proc (n) if `mod`(ithprime(n), 6) = 1 then ithprime(n) else end if end proc: A := [seq(a(n), n = 1 .. 100)]: seq(A[j]*A[j+1]*A[j+2], j = 1 .. 30); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 21 2009]
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CROSSREFS
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Cf. A001235, A002476, A011541, A154716, A154717, A154729.
Adjacent sequences: A154725 A154726 A154727 this_sequence A154729 A154730 A154731
Sequence in context: A062924 A130859 A154716 this_sequence A033502 A050794 A138130
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KEYWORD
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easy,nonn
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Jan 18 2009, Jan 21 2009
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EXTENSIONS
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Extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 21 2009
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