OFFSET
3,5
REFERENCES
S. P. Hurd and J. S. McCranie, Quantum factorials. Proceedings of the Twenty-fifth Southeastern International Conference on Combinatorics, Graph Theory and Computing (Boca Raton, FL, 1994). Congr. Numer. 104 (1994), 19-24.
LINKS
T. D. Noe, Table of n, a(n) for n = 3..2000
S. P. Hurd and J. S. McCranie, Quantum factorials, 1994.
FORMULA
a(n) = 0 iff n is odd and not a prime congruent to 3 modulo 4. - Charlie Neder, Feb 24 2019
MAPLE
a:= n-> (d-> irem(d(n-1)-d(n-2), n))(doublefactorial):
seq(a(n), n=3..100); # Alois P. Heinz, Dec 17 2021
MATHEMATICA
Table[Mod[(n-1)!!-(n-2)!!, n], {n, 3, 100}] (* Harvey P. Dale, Aug 07 2012 *)
CROSSREFS
KEYWORD
nonn,easy,nice
AUTHOR
STATUS
approved