id:A080979 - OEIS Search Results

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Each tree encoded in A014486 mapped to the corresponding branch-reduced zigzag-tree (positions in A014486).

+0
5

0, 1, 2, 3, 2, 5, 6, 7, 3, 2, 5, 11, 12, 5, 6, 15, 16, 7, 18, 6, 20, 7, 3, 2, 5, 11, 12, 5, 11, 29, 30, 12, 32, 11, 34, 12, 5, 6, 15, 39, 40, 15, 16, 43, 16, 7, 18, 47, 48, 49, 18, 6, 15, 53, 20, 55, 16, 57, 7, 18, 6, 20, 20, 7, 3, 2, 5, 11, 12, 5, 11, 29, 30, 12, 32, 11, 34, 12, 5, 11, 29 (list; graph; listen)

	OFFSET	`0,3`
	COMMENT	`For trees which are already branch-reduced we have a(n)=n, where n is one of A080980.`
	REFERENCES	`R. Donaghey, Automorphisms on Catalan trees and bracketing, J. Combin. Theory, Series B, 29 (1980), 75-90.`
	LINKS	`A. Karttunen, Gatomorphisms - with the complete Scheme source`
	PROGRAM	`(Scheme-function implementing this surjection on trees represented as S-expressions:) (define (BranchReducedZigzagTree! bt) (cond ((pair? bt) (cond ((and (pair? (car bt)) (not (null? (caar bt))) (null? (cdar bt))) (set-car! bt (caar bt)) (BranchReducedZigzagTree! bt)) ((and (pair? (cdr bt)) (not (null? (cddr bt))) (null? (cadr bt))) (set-cdr! bt (cddr bt)) (BranchReducedZigzagTree! bt)) (else (BranchReducedZigzagTree! (car bt)) (BranchReducedZigzagTree! (cdr bt)))))) bt)`
	CROSSREFS	`Same sequence sorted, with duplicates removed: A080980. Cf. A080293.` `Sequence in context: A052410 A072775 A090078 this_sequence A062789 A066069 A019530` `Adjacent sequences: A080976 A080977 A080978 this_sequence A080980 A080981 A080982`
	KEYWORD	`nonn`
	AUTHOR	`Antti Karttunen (my_firstname.my_surname(AT)iki.fi) Mar 02 2003`

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Last modified March 20 09:10 EDT 2010. Contains 173642 sequences.

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