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A053623
Number of distinct non-extendable sequences (x(1),x(2),...,x(k)) such that each x(i) is in {1,2,...,n} and (x(j) AND x(i)) <> x(j) for i=2..k, j=1..i-1.
2
1, 2, 4, 14, 38, 126, 252, 1662, 7180, 39430, 111064, 803876, 2863992, 12123360, 24246720, 329012784, 2602608516
OFFSET
1,2
REFERENCES
Related to Mathematical Recreations, Scientific American, March 2000.
LINKS
Sean A. Irvine, Java program (github)
EXAMPLE
a(3)=4, since the allowable sequences are (1,2), (2,1), (3,1,2), (3,2,1).
(1,3) is not allowed because 1 AND 3 = 01 AND 11 (base 2) = 1.
(3,1) is not allowed because it can be extended to (3,1,2).
CROSSREFS
Cf. A054668.
Sequence in context: A216630 A006611 A007462 * A035010 A349450 A055540
KEYWORD
nonn
AUTHOR
John W. Layman, Mar 21 2000
EXTENSIONS
a(17) from Sean A. Irvine, Jan 04 2022
STATUS
approved