A013189 All terms are squares and a(n) is length of n-th run.

1, 4, 4, 4, 4, 9, 9, 9, 9, 16, 16, 16, 16, 25, 25, 25, 25, 36, 36, 36, 36, 36, 36, 36, 36, 36, 49, 49, 49, 49, 49, 49, 49, 49, 49, 64, 64, 64, 64, 64, 64, 64, 64, 64, 81, 81, 81, 81, 81, 81, 81, 81, 81, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100

Offset: 1

Author

James Propp

Keywords

• nonn
• easy

Comments

Golomb's sequence using squares. - Benoit Cloitre, Apr 20 2003

Links

• Ivan Neretin, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001462, A080605, A080606, A080607.

Programs

Mathematica

f[s_] := Join@@Table[i^2, {i, Length[s]}, {s[[i]]}]; Nest[f, {1, 4}, 3]

Formula

n-th term, divided by n, tends to square root of two.