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A134952
Number of prime implicants of the Y function of order n.
1
1, 3, 10, 32, 113, 446, 2038, 11251, 77689, 685089, 7798812
OFFSET
0,2
COMMENTS
The Y function of order n is a self-dual monotone Boolean function of (n+1)(n+2)/2 points arranged in a triangular grid, with n+1 points on each side. Suppose we place black or white stones on that grid.
Then, as apparently first pointed out by John Milnor about 1950, either the white or black stones form a "Y" - that is, they touch all three sides of the board. (The corner points each touch two of the sides.)
The Y function tells us whether the white stones or the black stones have the Y.
REFERENCES
D. E. Knuth, The Art of Computer Programming, Vol. 4A, Exercise 7.1.1-67.
CROSSREFS
Cf. A134953.
Sequence in context: A261058 A306295 A356499 * A184436 A149028 A174573
KEYWORD
nonn,more
AUTHOR
Don Knuth, Jan 26 2008
STATUS
approved