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A071406
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a(n) is the smallest multiplier of n! such that -1+a(n)*n! and 1+a(n)*n! are both primes.
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3
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4, 2, 1, 3, 2, 17, 7, 6, 3, 14, 29, 30, 48, 27, 9, 24, 12, 97, 78, 47, 71, 80, 55, 13, 57, 20, 81, 259, 108, 163, 81, 118, 63, 215, 173, 513, 420, 561, 537, 1162, 158, 33, 122, 286, 459, 391, 305, 288, 114, 307, 15, 680, 355, 365, 338, 70, 23
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Pierre CAMI, Table of n, a(n) for n = 1..300
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EXAMPLE
| n=7: a(7)=7, 7!=5040, 7.7!=35280 and {35279,35281} are primes.
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MATHEMATICA
| Table[fl=1; Do[s=(j!)*k; If[PrimeQ[s-1]&&PrimeQ[s+1]&&Equal[fl, 1], Print[{j, k}]; fl=0], {k, 1, 2*j^2}], {j, 0, 100}]
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CROSSREFS
| Cf. A063983, A071256, A060256.
Sequence in context: A200586 A097525 A010124 * A010311 A023528 A105698
Adjacent sequences: A071403 A071404 A071405 * A071407 A071408 A071409
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), May 24 2002
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