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A279623
a(n) = smallest prime factor of n-th Bell number, or 1 if there are none.
3
1, 1, 2, 5, 3, 2, 7, 877, 2, 3, 5, 2, 37, 27644437, 2, 5, 241, 2, 7, 271, 2, 3, 3, 2, 3, 13, 2, 47, 5, 2, 3, 11, 2, 5694673, 3, 2, 29, 3, 2, 6353, 3221, 2, 35742549198872617291353508656626642567, 3, 2, 5, 5, 2, 3, 7615441337805454611187, 2
OFFSET
0,3
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..131 (terms 0..100 from Robert G. Wilson v)
FORMULA
a(n) = A020639(A000110(n)). - Robert Israel, Dec 25 2016
MATHEMATICA
f[n_] := (FactorInteger@ BellB@ n)[[1, 1]]; Array[f, 50, 0]
PROG
(Magma) [1, 1] cat [Minimum(PrimeDivisors(Bell(n))): n in [2..50]];
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Dec 25 2016
STATUS
approved