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A053708
Nearest prime to n! (but not equal to n!).
1
2, 3, 5, 23, 113, 719, 5039, 40343, 362867, 3628789, 39916801, 479001599, 6227020777, 87178291199, 1307674368043, 20922789888023, 355687428096031, 6402373705728037, 121645100408832089, 2432902008176640029, 51090942171709439969, 1124000727777607680031, 25852016738884976639911
OFFSET
1,1
COMMENTS
If n! is the average of its closest prime neighbors then the smaller prime is to be chosen (as in A051701).
LINKS
EXAMPLE
For 8! = 40320 the closest upper and lower primes are 40289 and 40343 with d = 31 and d = 23, so 40343 is closer to 8! than the lower neighbor.
MATHEMATICA
f[n_]:=Module[{nf=n!, s, l}, s=NextPrime[nf, -1]; l=NextPrime[nf]; If[nf-s>l-nf, l, s]]
Table[f[i], {i, 25}] (* Harvey P. Dale, Dec 08 2010 *)
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
Labos Elemer, Feb 10 2000
EXTENSIONS
Corrected by Rick L. Shepherd, Jan 11 2006
a(21)-a(23) from Amiram Eldar, Mar 10 2025
STATUS
approved