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A079780
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a(n) = largest prime <= n*prime(n).
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2
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2, 5, 13, 23, 53, 73, 113, 151, 199, 283, 337, 443, 523, 601, 701, 839, 997, 1097, 1259, 1409, 1531, 1733, 1907, 2131, 2423, 2621, 2777, 2971, 3137, 3389, 3931, 4177, 4519, 4723, 5209, 5431, 5807, 6173, 6491, 6917, 7333, 7591, 8209, 8467, 8863, 9151, 9907
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OFFSET
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1,1
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COMMENTS
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a(n) is the largest prime < A079779(n).
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LINKS
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FORMULA
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MAPLE
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With exception of first term: seq(prevprime(n*ithprime(n)), n=2..40);
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MATHEMATICA
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PrevPrim[n_] := Block[{k = n - 1}, While[ !PrimeQ[k], k-- ]; k]; Table[ Abs[ PrevPrim[ n*Prime[n]]], {n, 1, 50}]
Table[Abs[NextPrime[n Prime[n], -1]], {n, 50}] (* Harvey P. Dale, May 25 2012 *)
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PROG
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(PARI) for(n=1, 47, print1(precprime(n*prime(n)), ", "))
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CROSSREFS
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KEYWORD
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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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