A131655 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.

1, 8, 89, 1482, 33737, 974860, 34078585, 1397335710, 65753020657, 3493075453208, 206827445591945, 13508998509463890, 965035059918868889, 74859785094041370724, 6267261735949374860857, 563289843479215734940710, 54100963704277853262416833

Offset

1,2

Comments

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

Links

Alois P. Heinz, Table of n, a(n) for n = 1..300

Mikelis Emils Mikelsons, List of expressions for a(5)

Formula

a(n) = Sum_{i=1..n) binomial(n,i)*A140606(i). - Mikelis Emils Mikelsons, Sep 01 2021

Example

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.

Crossrefs

Cf. A133568, A140606.

Sequence in context: A295244 A264072 A303056 * A105718 A045732 A371208

Adjacent sequences: A131652 A131653 A131654 * A131656 A131657 A131658

Keyword

nonn

Author

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

Extensions

Definition corrected by Rick L. Shepherd, Sep 16 2007

a(5)-a(17) from Mikelis Emils Mikelsons, Sep 01 2021

Status

approved