A131655 - OEIS

%I #16 Sep 22 2024 04:34:45

%S 1,8,89,1482,33737,974860,34078585,1397335710,65753020657,

%T 3493075453208,206827445591945,13508998509463890,965035059918868889,

%U 74859785094041370724,6267261735949374860857,563289843479215734940710,54100963704277853262416833

%N Maximal number of different numbers that can be formed from n numbers using addition, subtraction, multiplication and division, when each number is used no more than once in a given expression.

%C See triangle A133568: Each row gives the least sequence of n positive integers such that a(n) distinct numbers are generated by these operations. - _Rick L. Shepherd_, Sep 16 2007

%H Alois P. Heinz, <a href="/A131655/b131655.txt">Table of n, a(n) for n = 1..300</a>

%H Mikelis Emils Mikelsons, <a href="/A131655/a131655.txt">List of expressions for a(5)</a>

%F a(n) = Sum_{i=1..n} binomial(n,i)*A140606(i). - _Mikelis Emils Mikelsons_, Sep 01 2021

%e a(2) = 8 : from two variables x and y we obtain the eight functions x, y, x+y, x*y, x-y, y-x, x/y and y/x.

%Y Cf. A133568, A140606.

%K nonn

%O 1,2

%A Daniel Rainjonneau (d.rainjonneau(AT)wanadoo.fr), Sep 11 2007

%E Definition corrected by _Rick L. Shepherd_, Sep 16 2007

%E a(5)-a(17) from _Mikelis Emils Mikelsons_, Sep 01 2021