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A112600 Smallest prime factor of A111392(n). 0
2, 5, 11, 37, 13, 23, 19, 23, 37, 127, 47, 61, 61, 47, 67, 61, 277, 83, 79, 97, 127, 83, 101, 131, 269, 109, 131, 109, 113, 157, 137, 181, 157, 181, 151, 173, 173, 179, 173, 211, 223, 251, 193, 197, 223, 233, 223, 251, 271, 241, 239, 269, 293, 281, 313, 347, 293 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
For all i, if i<n+2 then GCD(p_i,A111392(n))=1, where p_i is i-th prime.
A111392: a(n) = Product_{i=1..n-1} (Product_{k=1..i} p_k + Product_{k=i+1..n} p_k). - Robert G. Wilson v, Dec 22 2005
LINKS
MATHEMATICA
f[n_] := Product[(Product[Prime[k], {k, i}] + Product[Prime[k], {k, i + 1, n}]), {i, n - 1}]; f[1] = 2; g[n_] := Block[{k = 1}, While[Mod[f[n], Prime[k]] != 0, k++ ]; Prime@k]; Array[g, 20] (* Robert G. Wilson v *)
CROSSREFS
Cf. A111392.
Sequence in context: A295495 A343463 A130622 * A156014 A268397 A261438
KEYWORD
nonn
AUTHOR
Yasutoshi Kohmoto, Dec 15 2005
EXTENSIONS
More terms from Robert G. Wilson v, Dec 22 2005
STATUS
approved

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Last modified July 20 05:30 EDT 2024. Contains 374441 sequences. (Running on oeis4.)