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Search: id:A103804
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| A103804 |
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Primes p such that both 2p +/- 21 are primes. |
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+0
3
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| 5, 13, 19, 29, 31, 41, 59, 79, 89, 101, 109, 131, 179, 211, 239, 241, 271, 311, 331, 349, 409, 421, 449, 499, 509, 521, 541, 601, 619, 701, 751, 821, 839, 881, 1009, 1091, 1181, 1201, 1319, 1321, 1399, 1429, 1459, 1489, 1531, 1571, 1619, 1801, 1949, 1951
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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If -11 is not prime (Mathematica considers -prime as prime), then the first term, 5, should be omitted.
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FORMULA
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p, 2p-21, and 2p+21 all are primes.
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MATHEMATICA
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Select[Range[2000], PrimeQ[ # ] && PrimeQ[2# + 21] && PrimeQ[2# - 21] &]
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CROSSREFS
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Cf. A103802, A103803.
Adjacent sequences: A103801 A103802 A103803 this_sequence A103805 A103806 A103807
Sequence in context: A118915 A084442 A023270 this_sequence A129919 A045454 A002540
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Feb 16 2005
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