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A082858 Array A(x,y): the greatest common subtree (intersect) of the binary trees x and y, (x,y) running as (0,0),(1,0),(0,1),(2,0),(1,1),(0,2) and each index referring to a binary tree encoded by A014486(j). 5
0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 2, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 2, 3, 2, 1, 0, 0, 1, 2, 1, 1, 2, 1, 0, 0, 1, 2, 1, 4, 1, 2, 1, 0, 0, 1, 1, 3, 2, 2, 3, 1, 1, 0, 0, 1, 1, 3, 2, 5, 2, 3, 1, 1, 0, 0, 1, 2, 3, 1, 2, 2, 1, 3, 2, 1, 0, 0, 1, 2, 1, 1, 1, 6, 1, 1, 1, 2, 1, 0, 0, 1, 2, 1, 4, 1, 3, 3, 1, 4, 1, 2, 1, 0, 0, 1, 2, 1, 4, 2, 3, 7, 3, 2, 4, 1, 2, 1, 0 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,13

COMMENTS

Note that together with A082860 this forms a distributive lattice, thus it is possible to compute this function also with the binary AND-operation (A004198) with the help of appropriate mapping functions. I.e. we have A(x,y) = A082857(A004198(A082856(x), A082856(y))).

LINKS

Table of n, a(n) for n=0..119.

A. Karttunen, Alternative Catalan Orderings (with the complete Scheme source)

Index entries for sequences related to lattices

PROG

(Scheme-functions showing the essential idea. For the full source, follow the "Alternative Catalan Orderings" link.)

(define (A082858 n) (A080300 (parenthesization->binexp (GCSB (binexp->parenthesization (A014486 (A025581 n))) (binexp->parenthesization (A014486 (A002262 n)))))))

(define (GCSB t1 t2) (cond ((or (not (pair? t1)) (not (pair? t2))) (list)) (else (cons (GCSB (car t1) (car t2)) (GCSB (cdr t1) (cdr t2))))))

(define (A082858v2 n) (A082857 (A004198bi (A082856 (A025581 n)) (A082856 (A002262 n)))))

CROSSREFS

Cf. A072764. The lower/upper triangular region: A082859. Cf. A080300, A025581, A002262.

Sequence in context: A117201 A060953 A339367 * A255318 A249223 A115953

Adjacent sequences:  A082855 A082856 A082857 * A082859 A082860 A082861

KEYWORD

nonn,tabl

AUTHOR

Antti Karttunen May 06 2003

STATUS

approved

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Last modified July 29 17:41 EDT 2021. Contains 346346 sequences. (Running on oeis4.)