OFFSET
1,1
COMMENTS
Complement of A000389. Numbers k such that 120*k is not a product of 5 consecutive integers.
LINKS
FORMULA
a(n) = n+m if n+m>binomial(m+4,5), a(n) = n+m-2 if n+m-2<binomial(m+3,5) and a(n) = n+m-1 otherwise where m = floor((120n)^(1/5)).
PROG
(Python)
from math import comb
from sympy import integer_nthroot
def A377313(n): return n+(m:=integer_nthroot(120*n, 5)[0])+(0 if n>(k:=comb(m+4, 5)-m) else -2 if n-2<k-comb(m+3, 4) else -1)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Chai Wah Wu, Oct 24 2024
STATUS
approved