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A118455
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a(1)=1, a(n) = Product_{k=2..n} P(k), where P(k) is the largest prime <= k.
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6
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1, 2, 6, 18, 90, 450, 3150, 22050, 154350, 1080450, 11884950, 130734450, 1699547850, 22094122050, 287223586650, 3733906626450, 63476412649650, 1079099015044050, 20502881285836950, 389554744430902050
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OFFSET
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1,2
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LINKS
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EXAMPLE
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a(6)=450 because the largest primes that do not exceed 2,3,4,5 and 6 are, respectively 2,3,3,5 and 5, having product 2*3*3*5*5=450.
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MAPLE
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a:=proc(n) if n=1 then 1 else product(prevprime(k+1), k=2..n) fi end: seq(a(n), n=1..23); # Emeric Deutsch, Apr 30 2006
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MATHEMATICA
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FoldList[Times, 1, Table[Prime@ PrimePi@ k, {k, 2, 20}]] (* Michael De Vlieger, Aug 21 2017 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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