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A078096
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Least m such that P + m is a prime, where P is the n-th perfect number.
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0
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1, 1, 3, 19, 1, 7, 1, 105, 37, 163, 73, 43, 45, 649, 3753, 5323, 423, 3123
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Some of the larger entries may only correspond to probable primes.
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EXAMPLE
| a(3)=3 because 496 + 3 is a prime.
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MATHEMATICA
| e (* from A000043 *) = {2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203, 2281, 3217, 4253, 4423, ...}; NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; Do[p = 2^(e[[n]] - 1)*(2^e[[n]] - 1); Print[NextPrim[p] - p], {n, 1, 20}]
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CROSSREFS
| Cf. A061644, A000396, A000043.
Sequence in context: A157580 A101293 A189799 * A139429 A114365 A179767
Adjacent sequences: A078093 A078094 A078095 * A078097 A078098 A078099
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KEYWORD
| hard,more,nonn
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AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), Dec 01 2002
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EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 03 2002
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