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A110423
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a(n) = (n+1)(n+2)...(n+prime(k)) where prime(k) <= n < prime(k+1).
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2
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12, 120, 210, 30240, 55440, 17297280, 32432400, 57657600, 98017920, 28158588057600, 53970627110400, 64764752532480000, 124903451312640000, 233153109116928000, 422590010274432000, 830034394580628357120000
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OFFSET
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2,1
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LINKS
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FORMULA
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a(p) = (2p)!/p! if p is a prime.
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EXAMPLE
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a(6) = 7*8*9*10*11 = 55440.
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MAPLE
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p:=proc(n) if isprime(n)=true then n else prevprime(n) fi end: a:=n->product(n+j, j=1..p(n)): seq(a(n), n=2..19); # p is a modified prevprime command (for n prime yields n rather than the previous prime) # Emeric Deutsch, Aug 07 2005
# Simpler alternative:
seq((n+prevprime(n+1))!/n!, n=2..20); # Robert Israel, Aug 18 2019
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MATHEMATICA
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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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