A086290 - OEIS

%I #9 Jan 06 2020 08:36:13

%S 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,

%T 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,

%U 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

%N Minimal exponent in prime factorization of 7-smooth numbers.

%H Amiram Eldar, <a href="/A086290/b086290.txt">Table of n, a(n) for n = 1..10000</a>

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

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

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

%Y Cf. A002473, A051904, A086289, A086291.

%K nonn

%O 1,4

%A _Reinhard Zumkeller_, Jul 15 2003