OFFSET
0,4
COMMENTS
For n > 1, the factorial base representation of a(n) is {n-2, n-3, ..., 1, 0}, i.e., the numbers 0..(n-2) in descending order. - Amiram Eldar, Apr 24 2021
LINKS
Harry J. Smith, Table of n, a(n) for n = 0..100
FORMULA
MATHEMATICA
Table[ n! - Sum[k!, {k, 0, n - 1} ], {n, 0, 20} ]
PROG
(PARI) a(n) = n! - sum(k=0, n-1, k!); \\ Harry J. Smith, Oct 17 2009
(Python)
from sympy import factorial
left_factorial = lambda n: left_factorial(n - 1) + factorial(n - 1) if n > 0 else 0
a = lambda n: factorial(n) - left_factorial(n) # Darío Clavijo, Feb 16 2024
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Floor van Lamoen, Oct 31 2001
STATUS
approved