OFFSET
0,2
COMMENTS
k+1 is not a prime.
a(n) + 1 is 17-smooth in DATA. - David A. Corneth, Mar 15 2019
But fails at n 99, 114, 125, 127, 130, 135, 143, 146, ... - Michel Marcus, Apr 30 2019
FORMULA
EXAMPLE
For n = 1, 1! = 1 is not divisible by 2, 2! = 2 is not divisible by 3, 3! = 6 is not divisible by 4, 4! = 24 is not divisible by 5, and 5! = 120 is divisible by 6 but not 36. Therefore a(1) = 5. - Michael B. Porter, Apr 21 2019
MATHEMATICA
Array[Block[{k = 1}, While[Nand[Mod[k!, (k + 1)^#] == 0, Mod[k!, (k + 1)^(# + 1)] != 0], k++]; k] &, 58] (* Michael De Vlieger, Mar 11 2019 *)
PROG
(PARI) a(n) = {my(k=1); while((k! % (k+1)^n) || !(k! % (k+1)^(n+1)), k++); k; }
CROSSREFS
KEYWORD
nonn
AUTHOR
Jinyuan Wang, Mar 09 2019
STATUS
approved