A180491 Product of remainders of n mod k, for k = 2,3,4,...,n-1.

1, 1, 1, 0, 2, 0, 6, 0, 0, 0, 720, 0, 2160, 0, 0, 0, 2419200, 0, 65318400, 0, 0, 0, 754427520000, 0, 0, 0, 0, 0, 32953394073600000, 0, 311409573995520000, 0, 0, 0, 0, 0, 37269497815783833600000, 0, 0, 0, 7890485108998805913600000000, 0

Offset

1,5

Comments

a(n) is zero where n is composite and is trivially less than or equal to n! when n is prime or 1.

a(n)=0 iff n is composite. See A180492. - Robert G. Wilson v, Sep 09 2010

Links

Table of n, a(n) for n=1..42.

Example

a(7) = (7 mod 2) * (7 mod 3) * (7 mod 4) * (7 mod 5) * (7 mod 6) = 1 * 1 * 3 * 2 * 1 = 6.

Mathematica

f[n_] := Times @@ Mod[n, Range[2, n - 1]]; Array[f, 42] (* Robert G. Wilson v, Sep 09 2010 *)

Crossrefs

Cf. A034386, A000142, A004125, A180492, A180493.

Sequence in context: A153059 A151336 A346092 * A329893 A047918 A321981

Adjacent sequences: A180488 A180489 A180490 * A180492 A180493 A180494

Keyword

nonn

Author

Carl R. White, Sep 08 2010

Status

approved