A232980 The Gauss factorial n_3!.

1, 1, 2, 2, 8, 40, 40, 280, 2240, 2240, 22400, 246400, 246400, 3203200, 44844800, 44844800, 717516800, 12197785600, 12197785600, 231757926400, 4635158528000, 4635158528000, 101973487616000, 2345390215168000, 2345390215168000, 58634755379200000, 1524503639859200000, 1524503639859200000

Offset

0,3

Comments

The Gauss factorial n_k! is defined to be Product_{1<=j<=n, gcd(j,k)=1} j.

Links

Table of n, a(n) for n=0..27.

J. B. Cosgrave and K. Dilcher, An introduction to Gauss factorials, Amer. Math. Monthly, 118 (2011), 810-828.

J. B. Cosgrave and K. Dilcher, The Gauss-Wilson theorem for quarter-intervals, Acta Mathematica Hungarica, Sept. 2013.

Maple

Gf:=proc(N, n) local j, k; k:=1;
for j from 1 to N do if gcd(j, n)=1 then k:=j*k; fi; od; k; end;
f:=n->[seq(Gf(N, n), N=0..40)];
f(3);

Prog

(Magma) k:=3; [IsZero(n) select 1 else &*[j: j in [1..n] | IsOne(GCD(j, k))]: n in [0..30]]; // Bruno Berselli, Dec 10 2013

Crossrefs

The Gauss factorials n_1!, n_2!, n_3!, n_5!, n_6!, n_7!, n_10!, n_11! are A000142, A055634, A232980-A232985 respectively.

Sequence in context: A102647 A318869 A060224 * A212307 A111605 A009544

Adjacent sequences: A232977 A232978 A232979 * A232981 A232982 A232983

Keyword

nonn

Author

N. J. A. Sloane, Dec 08 2013

Status

approved