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Search: id:A128928
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| A128928 |
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Smallest member p of a triple of primes (p,p+8,p+20). |
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+0
1
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| 3, 11, 23, 53, 59, 89, 131, 173, 191, 263, 359, 389, 401, 479, 593, 599, 653, 719, 1013, 1031, 1109, 1193, 1229, 1283, 1439, 1451, 1523, 1559, 1601, 1733, 1979, 2273, 2531, 2663, 2699, 2711, 3041, 3209, 3251, 3299, 3323, 3449, 3491, 3539, 3623, 3719, 3911, 3923, 4091, 4211
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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A subsequence of A023202. The definition implies that the sum of the first two primes, 2(p+4), divides the sum of the product of the first two primes and the last, p(p+8)+p+20=(p+4)(p+5). This feature is shared with A022005 and common to prime triples of the format (p,p+2*a,p+a+a^2) with even a. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 26 2007
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MAPLE
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isA128928 := proc(n) isprime(n) and isprime(n+8) and isprime(n+20) ; end: for n from 1 to 300 do if isA128928(ithprime(n)) then printf("%d, ", ithprime(n)) ; fi ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 26 2007
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MATHEMATICA
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kmax = 580; Select[ Prime[ Range[1, kmax] ], (PrimeQ[ # + 8] && PrimeQ[ # + 20])& ] [Stuart Clary]
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CROSSREFS
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Cf. A022005.
Sequence in context: A141187 A107138 A145473 this_sequence A145477 A098828 A165635
Adjacent sequences: A128925 A128926 A128927 this_sequence A128929 A128930 A128931
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KEYWORD
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nonn
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AUTHOR
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J. M. Bergot (thekingfishb(AT)yahoo.ca), Apr 25 2007
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EXTENSIONS
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Corrected and extended by Robert G. Wilson v (rgwv(at)rgwv.com), R. J. Mathar (mathar(AT)strw.leidenuniv.nl) and Stuart Clary (clary(AT)uakron.edu), Apr 26 2007
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