A081810 If n = p_1^e_1 * ... * p_k^e_k, p_1 < ... < p_k primes, then a(n) = Max{ p_i*e_i }.

0, 2, 3, 4, 5, 3, 7, 6, 6, 5, 11, 4, 13, 7, 5, 8, 17, 6, 19, 5, 7, 11, 23, 6, 10, 13, 9, 7, 29, 5, 31, 10, 11, 17, 7, 6, 37, 19, 13, 6, 41, 7, 43, 11, 6, 23, 47, 8, 14, 10, 17, 13, 53, 9, 11, 7, 19, 29, 59, 5, 61, 31, 7, 12, 13, 11, 67, 17, 23, 7, 71, 6, 73, 37, 10, 19, 11, 13, 79, 8, 12

Offset: 1

Author

Benoit Cloitre, Apr 10 2003

Keywords

• nonn

Comments

If x and y are coprime then a(x*y) = max(a(x),a(y)). - Robert Israel, Nov 27 2017

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A081811 (with min).

Programs

Maple

f:= proc(n) max(seq(convert(t,`*`),t=ifactors(n)[2])) end proc:
f(1):= 0:
map(f, [$1..100]); # Robert Israel, Nov 27 2017

Mathematica

a[n_] := Module[{f = FactorInteger[n]}, Max[f[[All, 1]] f[[All, 2]]]];
Array[a, 100] (* Jean-François Alcover, Jul 19 2020 *)

PARI

a(n)=local(f); if(n==1,0,f=factor(n); vecmax(vector(matsize(f)[1],k,f[k,1]*f[k,2])))