login
A048642
Partial products of A003188 (Gray code).
3
1, 1, 3, 6, 36, 252, 1260, 5040, 60480, 786240, 11793600, 165110400, 1651104000, 18162144000, 163459296000, 1307674368000, 31384184832000, 784604620800000, 21184324761600000, 550792443801600000, 16523773314048000000
OFFSET
0,3
LINKS
FORMULA
a(0) = 1, a(n) = product(XOR(j, floor(j/2)), j=1..n).
a((2^n)-1) = A000142((2^n)-1) for all n.
MATHEMATICA
Join[{1}, FoldList[Times, Table[BitXor[n, Floor[n/2]], {n, 20}]]] (* Harvey P. Dale, Oct 05 2016 *)
PROG
(PARI) a(n) = prod(i=1, n, bitxor(i, i>>1)); \\ Michel Marcus, Apr 22 2013, Oct 02 2015
CROSSREFS
Sequence in context: A240986 A372003 A120595 * A264702 A077532 A174666
KEYWORD
easy,nonn
AUTHOR
Antti Karttunen, Jul 14 1999
STATUS
approved