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A103790
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a(n) = the minimum k that makes prime(n)+A019565(k) prime.
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2
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0, 1, 1, 3, 1, 3, 1, 5, 3, 1, 3, 3, 1, 5, 3, 3, 1, 3, 3, 1, 3, 5, 3, 9, 3, 1, 3, 1, 7, 9, 5, 3, 1, 5, 1, 3, 3, 5, 3, 3, 1, 5, 1, 3, 1, 7, 7, 3, 1, 5, 3, 1, 5, 3, 3, 3, 1, 3, 3, 1, 5, 9, 3, 1, 13, 7, 3, 5, 1, 5, 3, 7, 3, 3, 5, 3, 7, 11, 7, 5, 1, 5, 1, 3, 5, 3, 7, 3, 1, 15, 11, 7, 13, 7, 5, 3, 9, 1, 13, 3, 5, 3, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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COMMENTS
| All elements except the first one are odd. This suggests a new way looking for large primes candidates.
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EXAMPLE
| Prime(1)+A019565(0)=2+1=3 is prime, so a(1)=0;
Prime(4)+A019565(3)=7+6=13 is prime, so a(4)=3;
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MATHEMATICA
| A019565 = Function[tn, k1 = tn; o = 1; tt = 1; While[k1 > 0, k2 = Mod[k1, 2]; If[k2 == 1, tt = tt*Prime[o]]; k1 = (k1 - k2)/2; o = o + 1]; tt]; Do[npd = Prime[n]; ts = 1; tt = ts; cp = npd + A019565[tt]; While[ ! (PrimeQ[cp]), ts = ts + 1; tt = ts; cp = npd + A019565[ tt]]; Print[ts], {n, 3, 200} ]
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CROSSREFS
| Cf. A019565.
Sequence in context: A095660 A035648 A053575 * A193583 A013603 A157892
Adjacent sequences: A103787 A103788 A103789 * A103791 A103792 A103793
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KEYWORD
| easy,nonn
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AUTHOR
| Lei Zhou (lzhou5(AT)emory.edu), Feb 16 2005
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