This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A131655 #16 Sep 22 2024 04:34:45
%S A131655 1,8,89,1482,33737,974860,34078585,1397335710,65753020657,
%T A131655 3493075453208,206827445591945,13508998509463890,965035059918868889,
%U A131655 74859785094041370724,6267261735949374860857,563289843479215734940710,54100963704277853262416833
%N 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.
%C A131655 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 A131655 Alois P. Heinz, <a href="/A131655/b131655.txt">Table of n, a(n) for n = 1..300</a>
%H A131655 Mikelis Emils Mikelsons, <a href="/A131655/a131655.txt">List of expressions for a(5)</a>
%F A131655 a(n) = Sum_{i=1..n} binomial(n,i)*A140606(i). - _Mikelis Emils Mikelsons_, Sep 01 2021
%e A131655 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 A131655 Cf. A133568, A140606.
%K A131655 nonn
%O A131655 1,2
%A A131655 Daniel Rainjonneau (d.rainjonneau(AT)wanadoo.fr), Sep 11 2007
%E A131655 Definition corrected by _Rick L. Shepherd_, Sep 16 2007
%E A131655 a(5)-a(17) from _Mikelis Emils Mikelsons_, Sep 01 2021