A048643 Differences between partial products of Gray code (A048642) and factorials (A000142).

0, 0, 1, 0, 12, 132, 540, 0, 20160, 423360, 8164800, 125193600, 1172102400, 11935123200, 76281004800, 0, 10461394944000, 428917192704000, 14781951055872000, 429147343392768000, 14090871305871360000, 461146030563778560000, 13730871481551544320000, 390084405122331279360000

Offset

0,5

Comments

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

Links

Table of n, a(n) for n=0..23.

Formula

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

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

Prog

(PARI) a(n) = prod(i=1, n, bitxor(i, i>>1)) - n!; \\ Michel Marcus, Oct 02 2015

Crossrefs

Cf. A000142, A048642, A048644.

Sequence in context: A260018 A078218 A305261 * A111085 A002721 A340508

Adjacent sequences: A048640 A048641 A048642 * A048644 A048645 A048646

Keyword

easy,nonn

Author

Antti Karttunen, Jul 14 1999

Extensions

More terms from Michel Marcus, Oct 02 2015

Status

approved