OFFSET
1,3
COMMENTS
Nonzero entries in A180491. Note that this sequence, while increasing in general, is not strictly increasing.
a(n) is divisible by (n-1)!. - Robert G. Wilson v, Sep 09 2010
FORMULA
EXAMPLE
Since prime(4) = 7, a(4) = (7 mod 2) * (7 mod 3) * (7 mod 4) * (7 mod 5) * (7 mod 6) = 1 * 1 * 3 * 2 * 1 = 6.
MAPLE
a:= n-> (p-> mul(irem(p, k), k=2..p-1))(ithprime(n)):
seq(a(n), n=1..17); # Alois P. Heinz, Jul 16 2022
MATHEMATICA
f[n_]:=Times@@(Mod[n, # ]&/@ Range[2, n-1]); Table[f[Prime[i]], {i, 20}] (* Harvey P. Dale, Sep 18 2010 *)
f[n_] := Times @@ Mod[n, Range[2, n - 1]]; Table[ f@ Prime@ n, {n, 10}] (* Robert G. Wilson v, Sep 09 2010 *)
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
Carl R. White, Sep 08 2010
STATUS
approved