A111653 n-th composite number appears n times.

4, 6, 6, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 10, 12, 12, 12, 12, 12, 12, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 16, 18, 18, 18, 18, 18, 18, 18, 18, 18, 18, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 21

Offset: 1

Author

Jonathan Vos Post, Aug 12 2005

Keywords

• easy
• less
• nonn
• changed

Comments

A002808(n) appears n times.

Crossrefs

Cf. A002808, A111654, A111655.

Programs

Python

from math import isqrt
from sympy import composite
def A111653(n): return composite(isqrt(n<<3)+1>>1) # Chai Wah Wu, Sep 06 2025