OFFSET
1,2
FORMULA
EXAMPLE
a(2) = 14 because 4*6 = 24, the 2nd compositorial number is the 14th composite number: 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24.
MATHEMATICA
PROG
(Python)
from sympy import factorial, primepi, composite, primorial, compositepi
def A065899(n):
return compositepi(factorial(composite(n))//primorial(primepi(composite(n)))) # Chai Wah Wu, Sep 08 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Nov 28 2001
EXTENSIONS
One more term from Robert G. Wilson v, Nov 29 2001
a(11)-a(19) from Chai Wah Wu, Sep 08 2020
a(20) from Chai Wah Wu, Sep 09 2020
Name rewritten by Felix Fröhlich, Jun 01 2021
STATUS
approved