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Search: id:A104380
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| A104380 |
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Smallest prime p(i) such that between 2p(i) and 2p(i+1) there exist n primes. |
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+0
2
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| 59, 2, 5, 31, 89, 509, 113, 1129, 1951, 7253, 19609, 16141, 13339, 28229, 1327, 281431, 396733, 1122287, 461717, 370261, 2010733, 492113, 3279841, 14246971, 3117299, 5826001, 20831323
(list; graph; listen)
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OFFSET
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0,1
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EXAMPLE
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a(0)=59 because between 2*59=118 and 2*61=122 there are no primes and 59 is the least prime with this characteristic.
a(4)=89 because between 2*89=178 and 2*97=194 there are 4 primes, namely 179, 181, 191 and 193.
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MATHEMATICA
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f[n_] := PrimePi[2Prime[n + 1]] - PrimePi[2Prime[n]]; t = Table[0, {30}]; Do[a = f[n]; If[t[[a + 1]] == 0, t[[a + 1]] = Prime[n]], {n, 2500000}]; t
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CROSSREFS
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Cf. A102820, A060756.
Sequence in context: A128934 A116103 A116115 this_sequence A051321 A088665 A159250
Adjacent sequences: A104377 A104378 A104379 this_sequence A104381 A104382 A104383
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KEYWORD
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nonn
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AUTHOR
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Ali A. Tanara (tanara(AT)khayam.ut.ac.ir) and Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 03 2005
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