A048643 - OEIS

%I #8 Oct 02 2015 10:12:02

%S 0,0,1,0,12,132,540,0,20160,423360,8164800,125193600,1172102400,

%T 11935123200,76281004800,0,10461394944000,428917192704000,

%U 14781951055872000,429147343392768000,14090871305871360000,461146030563778560000,13730871481551544320000,390084405122331279360000

%N Differences between partial products of Gray code (A048642) and factorials (A000142).

%C a((2^n)-1) = 0 for all n.

%F a(0) = 0, a(n) = product(XORnos(j, floor(j/2)), j=1..n) - n!.

%F a(n) = A048642(n) - A000142(n).

%o (PARI) a(n) = prod(i=1, n, bitxor(i, i>>1)) - n!; \\ _Michel Marcus_, Oct 02 2015

%Y Cf. A000142, A048642, A048644.

%K easy,nonn

%O 0,5

%A _Antti Karttunen_, Jul 14 1999

%E More terms from _Michel Marcus_, Oct 02 2015