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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 (list; graph; refs; listen; history; text; internal format)
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.

LINKS

Table of n, a(n) for n=0..10.

CROSSREFS

Cf. A134953.

Sequence in context: A071718 A261058 A306295 * A184436 A149028 A174573

Adjacent sequences:  A134949 A134950 A134951 * A134953 A134954 A134955

KEYWORD

nonn,more

AUTHOR

Don Knuth, Jan 26 2008

STATUS

approved

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Last modified May 6 17:45 EDT 2021. Contains 343586 sequences. (Running on oeis4.)