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A134952
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Number of prime implicants of the Y function of order n.
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1
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1, 3, 10, 32, 113, 446, 2038, 11251, 77689, 685089, 7798812
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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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.
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REFERENCES
| D. E. Knuth, The Art of Computer Programming, Vol. 4A, Exercise 7.1.1-67.
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CROSSREFS
| Cf. A134953.
Sequence in context: A033505 A063782 A071718 * A184436 A149028 A174573
Adjacent sequences: A134949 A134950 A134951 * A134953 A134954 A134955
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KEYWORD
| nonn
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AUTHOR
| D. E. Knuth, Jan 26 2008
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