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A092969
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a(1) = 2; for n>1, a(n) = largest prime of the form n!/k + 1, where k < n, or 0 if no such prime exists.
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2
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2, 3, 7, 13, 61, 241, 2521, 20161, 72577, 604801, 39916801, 59875201, 3113510401, 17435658241, 186810624001, 10461394944001, 118562476032001, 0, 24329020081766401, 304112751022080001, 12772735542927360001
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Conjecture: There are only finitely many zeros in this sequence. In other words the sequence is identical to A092965 barring a finite set of terms which are zero.
I found zeros for n: 18,51,53,84,95,100,104,106,143,178,180,181,188,202,203,(204) - Robert G. Wilson v Mar 27 2004.
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MATHEMATICA
| f[n_] := Block[{k = 1}, While[ !PrimeQ[n!/k + 1], k++ ]; If[k < n, n!/k + 1, 0]]; Table[ f[n], {n, 22}] (from Robert G. Wilson v Mar 27 2004)
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PROG
| (PARI) a(n)=for (i=1, n, if(isprime(n!/i+1), return((n!/i+1))))
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CROSSREFS
| Cf. A092968, A092970.
Sequence in context: A104367 A104365 A104372 * A089136 A092965 A051454
Adjacent sequences: A092966 A092967 A092968 * A092970 A092971 A092972
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 26 2004
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EXTENSIONS
| More terms from Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 26 2004
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