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Search: id:A090076
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| A090076 |
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a(n) = prime(n)*prime(n+2). |
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+0
4
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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; listen)
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OFFSET
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1,1
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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)
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PROGRAM
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(Mupad) ithprime(i)*ithprime(i+2) $ i = 1..40 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 26 2007
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 square-free semiprimes, A006881. Cf. A006094, A090090.
Sequence in context: A067520 A042309 A048697 this_sequence A156592 A045973 A095679
Adjacent sequences: A090073 A090074 A090075 this_sequence A090077 A090078 A090079
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KEYWORD
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easy,nonn
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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 (rgwv(AT)rgwv.com), Jan 22 2004
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