A279623 a(n) = smallest prime factor of n-th Bell number, or 1 if there are none.

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

Cf. A000110, A020639, A139044, A144293.

Sequence in context: A302130 A156637 A195784 * A287040 A212887 A163766

Adjacent sequences: A279620 A279621 A279622 * A279624 A279625 A279626

Keyword

nonn

Author

Vincenzo Librandi, Dec 25 2016

Status

approved