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 A137840 #6 Jul 25 2023 12:20:49 %S A137840 4,256,4294967296,340282366920938463463374607431768211456, %T A137840 13407807929942597099574024998205846127479365820592393377723561443721764030073546976801874298166903427690031858186486050853753882811946569946433649006084096 %N A137840 Number of distinct n-ary operators in a quaternary logic. %C A137840 The total number of n-ary operators in a k-valued logic is T = k^(k^n), i.e. if S is a set of k elements, there are T ways of mapping an ordered subset of n elements taken from S to an element of S. Some operators are "degenerate": the operator has arity p, if only p of the n input values influence the output. Therefore the set of operators can be partitioned into n+1 disjoint subsets representing arities from 0 to n. %F A137840 a(n) = 4^(4^n). %Y A137840 Cf. A001146 (in binary logic), A055777 (in a ternary logic), A137841 (in a quinternary logic). %Y A137840 Subsequence of A000302. %K A137840 easy,nonn %O A137840 0,1 %A A137840 _Ross Drewe_, Feb 13 2008