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A075409 a(n) is the smallest m such that n!-m and n!+m are both primes. 3
0, 1, 5, 7, 19, 19, 31, 17, 11, 17, 83, 67, 353, 227, 163, 59, 61, 113, 353, 31, 1447, 571, 389, 191, 337, 883, 101, 1823, 659, 709, 163, 1361, 439, 307, 1093, 1733, 2491, 1063, 1091, 1999, 1439, 109, 2753, 607, 2617, 269, 103, 2663, 337, 14447, 2221, 5471, 2887 (list; graph; refs; listen; history; internal format)
OFFSET

2,3

COMMENTS

For n=3,5,10,21,171,190,348, n! is an interprime, the average of two consecutive primes, see A053709. In general n! may be average of several pairs of primes, in which case the minimal distance is in the sequence. See also n^n and n!! as average of two primes in A075468 and A075410.

EXAMPLE

a(4)=5 because 4!=24 and 19 and 25 are primes with smallest distance 5 from 4!.

CROSSREFS

Cf. A053709, A075468, A075410.

Sequence in context: A116623 A046151 A046078 * A058079 A076787 A094963

Adjacent sequences:  A075406 A075407 A075408 * A075410 A075411 A075412

KEYWORD

nonn

AUTHOR

Zak Seidov (zakseidov(AT)yahoo.com), Sep 18 2002

EXTENSIONS

More terms from David Wasserman (dwasserm(AT)earthlink.net), Jan 17 2005

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Last modified February 17 19:13 EST 2012. Contains 206085 sequences.