A086290 Minimal exponent in prime factorization of 7-smooth numbers.

0, 1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 1, 1, 4, 1, 1, 1, 1, 2, 3, 1, 1, 5, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 6, 1, 2, 1, 1, 4, 1, 1, 1, 1, 2, 1, 2, 1, 1, 3, 1, 7, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 3, 1, 2, 1, 5, 1, 1, 1, 8, 1, 1, 2, 1, 1, 1, 1, 2, 1, 3, 1, 1, 1, 1, 1, 2, 2, 1, 1, 3, 2, 1, 1

Offset

1,4

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A051904(A002473(n)).

a(n) <= A086291(n) <= A086289(n).

Mathematica

minExp[1] = 0; minExp[n_] := Min @@ Last /@ FactorInteger[n]; minExp/@Select[Range[500], Max[Transpose[FactorInteger[#]][[1]]] <= 7 &] (* Amiram Eldar, Jan 06 2020 *)

Crossrefs

Cf. A002473, A051904, A086289, A086291.

Sequence in context: A242012 A359165 A377364 * A136568 A342477 A372287

Adjacent sequences: A086287 A086288 A086289 * A086291 A086292 A086293

Keyword

nonn

Author

Reinhard Zumkeller, Jul 15 2003

Status

approved