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A090076
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a(n) = prime(n)*prime(n+2).
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6
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10, 21, 55, 91, 187, 247, 391, 551, 713, 1073, 1271, 1591, 1927, 2279, 2773, 3233, 3953, 4331, 4891, 5609, 6059, 7031, 8051, 8989, 9991, 10807, 11227, 12091, 13843, 14803, 17399, 18209, 20413, 20989, 23393, 24613, 26219, 28199, 29893, 31313
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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Subsequence of A192133. [Reinhard Zumkeller, Jun 26 2011]
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LINKS
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Table of n, a(n) for n=1..40.
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EXAMPLE
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a(5) = prime(5)*prime(7) = 11*17 = 187.
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MATHEMATICA
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Table[Prime[n] Prime[n + 2], {n, 1, 40}] (* from Robert G. Wilson v Jan 22 2004 *)
Last[#]First[#]&/@Partition[Prime[Range[50]], 3, 1] (* Harvey P. Dale, May 08 2013 *)
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PROG
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(Mupad) ithprime(i)*ithprime(i+2) $ i = 1..40 // Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 26 2007
(Sage)
def prime_gaps(n):
primegaps = []
nprimes = primes_first_n(n+1)
for i in range(2, n+1):
primegaps.append(nprimes[i]*nprimes[i-2])
return primegaps
print prime_gaps(60) # Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jul 08 2008
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CROSSREFS
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Subset of the squarefree semiprimes, A006881. Cf. A006094, A090090.
Sequence in context: A042309 A215757 A048697 * A156592 A045973 A095679
Adjacent sequences: A090073 A090074 A090075 * A090077 A090078 A090079
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KEYWORD
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easy,nonn,changed
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AUTHOR
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Felix Tubiana (fat2(AT)columbia.edu), Jan 21 2004
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EXTENSIONS
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Extended by Robert G. Wilson v, Jan 22 2004
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STATUS
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approved
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