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Search: id:A114233
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| A114233 |
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n(k) is the minimum number n that makes 2*Prime[k]+Prime[n] a prime, which matches n<k. |
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+0
5
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| 2, 2, 4, 2, 2, 2, 4, 2, 3, 3, 4, 2, 2, 2, 6, 3, 2, 4, 2, 3, 4, 2, 2, 11, 3, 6, 3, 2, 2, 4, 2, 2, 6, 3, 2, 3, 2, 2, 11, 3, 4, 2, 2, 2, 5, 2, 2, 2, 6, 6, 3, 4, 4, 11, 2, 3, 2, 4, 2, 4, 2, 8, 3, 4, 5, 2, 4, 2, 2, 14, 3, 3, 2, 2, 8, 2, 4, 2, 8, 5, 8, 5, 2, 14, 6, 3, 4, 2, 2, 6, 2, 11, 5, 2, 2, 4, 2, 3, 2, 2, 2, 6, 5
(list; graph; listen)
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OFFSET
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3,1
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EXAMPLE
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k=3: 2*Prime[3]+Prime[2]=2*5+3=13 is prime, so n(3)=2;
k=4: 2*Prime[4]+Prime[2]=2*7+3=17 is prime, so n(4)=2;
k=5: 2*Prime[5]+Prime[2]=2*11+3=25 is not prime
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2*Prime[5]+Prime[4]=2*11+7=29 is prime, so n(5)=4;
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MATHEMATICA
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Table[p1 = Prime[n1]; n2 = 1; p2 = Prime[n2]; While[cp = 2*p1 + p2; ! PrimeQ[cp], n2++; If[n2 >= n1, Print[n1]]; p2 = Prime[n2]]; n2, { n1, 3, 202}]
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CROSSREFS
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Cf. A073703, A114227, A114228, A114231.
Sequence in context: A092188 A097884 A094818 this_sequence A063086 A077636 A057000
Adjacent sequences: A114230 A114231 A114232 this_sequence A114234 A114235 A114236
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KEYWORD
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easy,nonn
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AUTHOR
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Lei Zhou (lzhou5(AT)emory.edu), Nov 20 2005
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