cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A122204 Signature permutations of ENIPS-transformations of non-recursive Catalan automorphisms in table A089840.

Original entry on oeis.org

0, 1, 0, 2, 1, 0, 3, 3, 1, 0, 4, 2, 2, 1, 0, 5, 8, 3, 2, 1, 0, 6, 7, 4, 3, 2, 1, 0, 7, 6, 6, 5, 3, 2, 1, 0, 8, 4, 5, 4, 5, 3, 2, 1, 0, 9, 5, 7, 6, 6, 6, 3, 2, 1, 0, 10, 22, 8, 7, 4, 5, 6, 3, 2, 1, 0, 11, 21, 9, 8, 7, 4, 4, 4, 3, 2, 1, 0, 12, 20, 14, 13, 8, 7, 5, 5, 4, 3, 2, 1, 0, 13, 17, 10, 12, 13
Offset: 0

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Author

Antti Karttunen, Sep 01 2006, Jun 06 2007

Keywords

Comments

Row n is the signature permutation of the Catalan automorphism which is obtained from the n-th nonrecursive automorphism in the table A089840 with the recursion scheme "ENIPS". In this recursion scheme the algorithm first recurses down to the right-hand side branch of the binary tree, before the given automorphism is applied at its root. This corresponds to the fold-right operation applied to the Catalan structure, interpreted e.g. as a parenthesization or a Lisp-like list, where (lambda (x y) (f (cons x y))) is the binary function given to fold, with 'f' being the given automorphism. The associated Scheme-procedures ENIPS and !ENIPS can be used to obtain such a transformed automorphism from any constructively or destructively implemented automorphism. Each row occurs only once in this table. Inverses of these permutations can be found in table A122203.
Because of the "universal property of folds", the recursion scheme ENIPS has a well-defined inverse, that is, it acts as a bijective mapping on the set of all Catalan automorphisms. Specifically, if g = ENIPS(f), then (f s) = (g (cons (car s) (g^{-1} (cdr s)))), that is, to obtain an automorphism f which gives g when subjected to recursion scheme ENIPS, we compose g with its own inverse applied to the cdr-branch of a S-expression (i.e. the right subtree in the context of binary trees). This implies that for any non-recursive automorphism f in the table A089840, ENIPS^{-1}(f) is also in A089840, which in turn implies that the rows of table A089840 form a (proper) subset of the rows of this table.

References

  • A. Karttunen, paper in preparation, draft available by e-mail.

Crossrefs

Cf. The first 22 rows of this table: row 0 (identity permutation): A001477, 1: A069768, 2: A057510, 3: A130342, 4: A130348, 5: A130346, 6: A130344, 7: A122282, 8: A082340, 9: A130354, 10: A130352, 11: A130350, 12: A057502, 13: A130364, 14: A130366, 15: A069770, 16: A130368, 17: A074686, 18: A130356, 19: A130358, 20: A130362, 21: A130360. Other rows: row 169: A089859, row 253: A123718, row 3608: A129608, row 3613: A072796, row 65167: A074679, row 79361: A123716.

A123503 An involution of nonnegative integers: signature permutation of a nonrecursive Catalan automorphism, row 253 of table A089840.

Original entry on oeis.org

0, 1, 2, 3, 4, 6, 5, 8, 7, 9, 10, 14, 16, 19, 11, 15, 12, 21, 22, 13, 20, 17, 18, 23, 24, 25, 26, 27, 37, 38, 42, 44, 47, 51, 53, 56, 60, 28, 29, 39, 43, 52, 30, 40, 31, 58, 59, 32, 62, 63, 64, 33, 41, 34, 57, 61, 35, 54, 45, 46, 36, 55, 48, 49, 50, 65, 66, 67, 68, 69, 70, 71
Offset: 0

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Author

Antti Karttunen, Oct 11 2006

Keywords

Comments

This automorphism either swaps (if A057515(n) > 1) the first two toplevel elements (of a general plane tree, like *A072796 does) and otherwise (if n > 1, A057515(n)=1) swaps the sides of the left hand side subtree of the S-expression (when viewed as a binary tree, like *A089854 does). This is illustrated below, where letters A, B and C refer to arbitrary subtrees located on those nodes and () stands for an implied terminal node.
...B...C.............A...C............A...B...........B...A
....\./...............\./..............\./.............\./
.A...x.....-->.....B...x................x..()....-->....x..()
..\./...............\./..................\./.............\./
...x....(A072796)....x....................x...(A089854)...x
(a . (b . c)) --> (b . (a . c)) / ((a . b) . ()) --> ((b . a) . ())
This is the first multiclause automorphism in table A089840 which cannot be represented as a composition of two smaller nonrecursive automorphisms, the property which is also shared by *A123499 and *A123500.

Crossrefs

Row 253 of A089840. Used to construct A123717 and A123718.

A123717 Signature permutation of a Catalan automorphism: row 253 of table A122203.

Original entry on oeis.org

0, 1, 2, 3, 4, 6, 5, 8, 7, 9, 11, 14, 16, 19, 10, 15, 13, 21, 22, 12, 20, 17, 18, 23, 25, 28, 30, 33, 37, 39, 42, 44, 47, 51, 53, 56, 60, 24, 29, 38, 43, 52, 27, 41, 35, 58, 59, 36, 62, 63, 64, 26, 40, 34, 57, 61, 31, 54, 45, 46, 32, 55, 48, 49, 50, 65, 67, 70, 72, 75, 79, 81
Offset: 0

Views

Author

Antti Karttunen, Oct 11 2006

Keywords

Comments

This is the signature-permutation of Catalan automorphism which is derived from nonrecursive Catalan automorphism *A123503 with the recursion schema SPINE (defined in A122203).
The number of fixed points in range [A014137(n-1)..A014138(n-1)] of this permutation begins as 1,1,2,1,3,1,4,1,8,1,16,1,47,..., the LCM of cycle sizes as 1,1,1,2,12,12,120,120,840,840,5040,5040,55440,... (cf. A089423) and the cycle-count sequence seems to be A045629. (To be proved.)

References

  • A. Karttunen, paper in preparation, draft available by e-mail.

Crossrefs

Inverse: A123718. a(n) = A057509(A089854(n)). Row 253 of A122203.
Showing 1-3 of 3 results.