OFFSET
1,1
COMMENTS
EXAMPLE
prime(1) = 2 and the greatest k with k! <= 2 is 2, so a(1) = 2.
prime(4) = 7 and the greatest k with k! <= 7 is 3, so a(4) = 3.
prime(10) = 29 and the greatest k with k! <= 29 is 4 so a(10) = 4.
Rows with n, prime(n), greatest k! <=n, a(n) for n = 1..14
n 1 2 3 4 5 6 7 8 9 10 11 12 13 14
prime(n) 2 3 5 7 11 13 17 19 23 29 31 37 41 43
greatest k! 2 2 2 6 6 6 6 6 6 24 24 24 24 24
a(n) 2 2 2 3 3 3 3 3 3 4 4 4 4 4
PROG
(PARI) a(n) = my(k=1); until (k! > prime(n), k++); k-1; \\ Michel Marcus, Jul 19 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Bernard Schott, Jul 16 2021
STATUS
approved