0,4

x[n]y is the square-bracket notation for hyperoperations.

See A054871 for details and key links.

Table of n, a(n) for n=0..5.

a(0) = 2[0]-2 = -1;

a(1) = 2[1]-1 = 1;

a(2) = 2[2]0 = 0;

a(3) = 2[3]1 = 2;

a(4) = 2[4]2 = 4;

a(6) = 2[5]3 = 65536;

a(7) = 2[6]4 = 2[6]2[6]2 = 2[7]3.

Cf. A001695 (2[n]n).

Sequence in context: A070655 A006263 A266198 * A079236 A138852 A062701

Adjacent sequences: A274987 A274988 A274989 * A274991 A274992 A274993

sign

Natan Arie Consigli, Sep 24 2016

approved