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Search: id:A114231
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| A114231 |
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n(k) is the minimum number that makes Prime[k]+2*Prime[k-n(k)] a prime. |
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+0
6
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| 1, 1, 1, 3, 3, 1, 1, 1, 2, 1, 3, 2, 4, 4, 2, 9, 1, 3, 2, 4, 5, 1, 5, 2, 8, 3, 1, 3, 1, 1, 3, 8, 2, 6, 1, 4, 3, 8, 2, 7, 7, 14, 9, 7, 1, 4, 3, 1, 1, 1, 5, 1, 1, 2, 8, 4, 1, 8, 2, 4, 1, 8, 3, 9, 5, 3, 2, 1, 4, 1, 4, 4, 2, 3, 2, 4, 2, 12, 3, 1, 1, 3, 12, 2, 1, 2, 5, 5, 3, 3, 10, 4, 19, 1, 6, 4, 8, 7, 2, 5, 9, 2, 3
(list; graph; listen)
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OFFSET
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2,4
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EXAMPLE
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k=2, Prime[2]+2*Prime[2-1]=3+2*2=7 is prime, so n(2)=1;
k=3, Prime[3]+2*Prime[3-1]=5+2*3=11 is prime, so n(3)=1;
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k=17, Prime[17]+2*Prime[17-9]=59+2*19=97 is prime, so n(17)=9
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MATHEMATICA
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Table[p1 = Prime[n1]; n2 = n1 - 1; p2 = Prime[n2]; While[cp = p1 + 2*p2; ! PrimeQ[cp], n2--; If[n2 == 0, Print[n1]]; p2 = Prime[n2]]; n1 - n2, {n1, 2, 201}]
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CROSSREFS
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Cf. A114231, A114227, A114228.
Sequence in context: A046532 A014421 A127197 this_sequence A079075 A086703 A072917
Adjacent sequences: A114228 A114229 A114230 this_sequence A114232 A114233 A114234
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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 18 2005
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