A111652 3n appears n times.

3, 6, 6, 9, 9, 9, 12, 12, 12, 12, 15, 15, 15, 15, 15, 18, 18, 18, 18, 18, 18, 21, 21, 21, 21, 21, 21, 21, 24, 24, 24, 24, 24, 24, 24, 24, 27, 27, 27, 27, 27, 27, 27, 27, 27, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 36, 36, 36, 36, 36

Offset: 1

Author

Jonathan Vos Post, Aug 12 2005

Keywords

• easy
• nonn

Crossrefs

Cf. A000194, A008585, A111650, A111651, A002024.

Programs

Mathematica

Flatten[Table[Table[3n,{n}],{n,15}]] (* Harvey P. Dale, Jul 23 2013 *)

Python

from math import isqrt
def A111652(n): return (m:=isqrt(n<<3)+1&-2)+(m>>1) # Chai Wah Wu, Jun 06 2025

Formula

a(n) = 3*A002024(n) = A111650(n)*3/2. - Chai Wah Wu, Jun 06 2025