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A257891
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Numbers that are products of at least three consecutive primes.
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2
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30, 105, 210, 385, 1001, 1155, 2310, 2431, 4199, 5005, 7429, 12673, 15015, 17017, 20677, 30030, 33263, 46189, 47027, 65231, 82861, 85085, 96577, 107113, 146969, 190747, 215441, 241133, 255255, 290177, 323323, 347261, 392863, 409457, 478661, 510510, 583573
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listen;
history;
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internal format)
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(5) = 1001 = 7 * 11 * 13;
a(6) = 1155 = 3 * 5 * 7 * 11;
a(7) = 2310 = 2 * 3 * 5 * 7 * 11;
a(8) = 2431 = 11 * 13 * 17.
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MATHEMATICA
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Select[Module[{nn=1000}, Flatten[Table[Times@@@Partition[Prime[Range[nn]], d, 1], {d, 3, 7}]]]//Union, #<10^7&] (* Harvey P. Dale, Aug 04 2024 *)
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PROG
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(Haskell)
import Data.Set (singleton, deleteFindMin, insert)
a257891 n = a257891_list !! (n-1)
a257891_list = f $ singleton (30, 2, 5) where
f s = y : f (insert (w, p, q') $ insert (w `div` p, a151800 p, q') s')
where w = y * q'; q' = a151800 q
((y, p, q), s') = deleteFindMin s
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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