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Search: id:A095389
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| A095389 |
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a[n] is the number of residues from reduced residue system, R, modulo 210 such that both R and R+2 are primes, i.e. both 210n+r and 210n+r+2 are primes at fixed n. |
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+0
6
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| 13, 7, 6, 5, 5, 4, 6, 5, 5, 6, 6, 2, 6, 2, 3, 6, 7, 3, 4, 6, 6, 4, 5, 4, 2, 3, 6, 4, 1, 4, 2, 5, 5, 3, 4, 4, 2, 2, 2, 4, 3, 2, 5, 2, 5, 2, 4, 4, 3, 5, 2, 2, 4, 2, 3, 2, 4, 4, 3, 1, 1, 4, 1, 2, 0, 6, 5, 2, 3, 4, 1, 0, 4, 1, 5, 1, 4, 3, 1, 3, 3, 3, 3, 3, 5, 7, 3, 2, 2, 0, 3, 3, 4, 2, 3, 4, 2, 4, 4, 3, 4, 2, 6, 3, 1
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Since arbitrary large prime gaps occur, thus several consecutive zeros may arise in the sequence.
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EXAMPLE
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n=0: only 13+2=15 integers corresponds to the condition: {11,17,29,41,59,71,101,107,137,149,179,191,197}, so a[0]=13; See A078859.
n=11:only 2 twins were found, {2339,2341} and {2381,2383} corresponding {29,31} and {71,73} residue-pairs.
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MATHEMATICA
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{k =0, ta=Table[0, {100}]}; Do[{m=0}; Do[s=210k+r; s1=210k+r+2; If[PrimeQ[s]&&PrimeQ[s+2], m=m+1], {r, 1, 210}]; ta[[k]]=m, {k, 1, 100}]; ta
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CROSSREFS
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Cf. A001359, A078859.
Sequence in context: A078438 A133723 A061045 this_sequence A110056 A076116 A010216
Adjacent sequences: A095386 A095387 A095388 this_sequence A095390 A095391 A095392
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KEYWORD
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nonn
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AUTHOR
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Labos E. and Enoch Haga (labos(AT)ana.sote.hu; Enokh(AT)comcast.net), Jun 15 2004
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