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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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

A002808(n) appears n times.

LINKS

Table of n, a(n) for n=1..73.

PROG

(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