OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = Product_{k = prevprime(n)..n} k, for n>=3 with a(1)=1, a(2)=2 and where prevprime = A151799. - Wesley Ivan Hurt, Dec 12 2021
EXAMPLE
a(10) = 10*9*8*7 = 5040 because 7 is the largest prime smaller than 10.
MATHEMATICA
a[1] = 1; a[2] = 2; a[n_] := n!/(NextPrime[n, -1] - 1)!; Array[a, 30] (* Amiram Eldar, Feb 08 2021 *)
PROG
(PARI) a(n) = if (n<=2, n, prod(k=0, n-precprime(n-1), n-k)); \\ Michel Marcus, Feb 09 2021
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), Apr 25 2006
EXTENSIONS
Offset and a(36) corrected by Amiram Eldar, Feb 08 2021
STATUS
approved