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A308938
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Smallest deficient number which is the product of n consecutive primes.
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0
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1, 2, 15, 105, 1155, 85085, 1616615, 37182145, 1078282205, 247357937827, 10141675450907, 436092044389001, 20496326086283047, 1086305282573001491, 64092011671807087969, 3909612711980232366109, 261944051702675568529303, 18598027670889965365580513
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OFFSET
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0,2
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COMMENTS
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a(n) is greater than A087234(n) for n = 2, 5, 6, 9, 10, 11, 12, 13, 14, 18, ... By definition, A087234(n) is never greater than a(n).
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LINKS
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EXAMPLE
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a(5) = 5*7*11*13*17 = 85085.
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MATHEMATICA
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a[n_] := Module[{p = Prime@Range[n]}, While[Times@@(1+1/p) >= 2, p = Rest @ AppendTo[p, NextPrime@p[[-1]]]]; Times@@p]; Array[a, 18, 0] (* Amiram Eldar, Jul 04 2019 *)
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PROG
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(PARI) a(n)=for(k=1, +oo, p=prod(i=k, k+n-1, prime(i)); sigma(p)<2*p && return(p))
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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