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Maximal GCD of five positive integers with sum n.
8

%I #15 Sep 21 2022 11:28:02

%S 1,1,1,1,1,2,1,2,1,2,3,2,1,3,1,4,3,2,1,4,5,2,3,4,1,6,1,4,3,2,7,6,1,2,

%T 3,8,1,7,1,4,9,2,1,8,7,10,3,4,1,9,11,8,3,2,1,12,1,2,9,8,13,11,1,4,3,

%U 14,1,12,1,2,15,4,11,13,1,16,9,2,1,14,17,2,3,11,1

%N Maximal GCD of five positive integers with sum n.

%t a[n_] := GCD @@@ IntegerPartitions[n, {5}] // Max;

%t Table[a[n], {n, 5, 100}] (* _Jean-François Alcover_, Sep 21 2022 *)

%o (PARI) a(n) = { my (v=0); forpart(p=n, v=max(v,gcd(Vec(p))),, [5,5]); v } \\ _Rémy Sigrist_, Jul 01 2022

%Y Cf. A008382, A129650.

%Y Maximal GCD of k positive integers with sum n for k = 2..10: A032742 (k=2,n>=2), A355249 (k=3), A355319 (k=4), this sequence (k=5), A355368 (k=6), A355402 (k=7), A354598 (k=8), A354599 (k=9), A354601 (k=10).

%K nonn

%O 5,6

%A _Wesley Ivan Hurt_, Jun 29 2022