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 1-5 of 5 results.

A122203 Signature permutations of SPINE-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, 7, 3, 2, 1, 0, 6, 8, 4, 3, 2, 1, 0, 7, 6, 6, 5, 3, 2, 1, 0, 8, 5, 5, 4, 5, 3, 2, 1, 0, 9, 4, 7, 6, 6, 6, 3, 2, 1, 0, 10, 17, 8, 7, 4, 5, 6, 3, 2, 1, 0, 11, 18, 9, 8, 7, 4, 4, 4, 3, 2, 1, 0, 12, 20, 11, 12, 8, 7, 5, 5, 4, 3, 2, 1, 0, 13, 21, 14, 13, 12
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 "SPINE". In this recursion scheme the given automorphism is first applied at the root of binary tree, before the algorithm recurses down to the new right-hand side branch. The associated Scheme-procedures SPINE and !SPINE 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 A122204.
The recursion scheme SPINE has a well-defined inverse, that is, it acts as a bijective mapping on the set of all Catalan automorphisms. Specifically, if g = SPINE(f), then (f s) = (cond ((pair? s) (let ((t (g s))) (cons (car t) (g^{-1} (cdr t))))) (else s)) that is, to obtain an automorphism f which gives g when subjected to recursion scheme SPINE, we compose g with its own inverse applied to the cdr-branch of a S-expression. This implies that for any non-recursive automorphism f in the table A089840, SPINE^{-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.

Links

Crossrefs

Cf. The first 22 rows of this table: row 0 (identity permutation): A001477, 1: A069767, 2: A057509, 3: A130341, 4: A130343, 5: A130345, 6: A130347, 7: A122282, 8: A082339, 9: A130349, 10: A130351, 11: A130353, 12: A074685, 13: A130355, 14: A130357, 15: A130359, 16: A130361, 17: A057501, 18: A130363, 19: A130365, 20: A130367, 21: A069770. Other rows: row 251: A089863, row 253: A123717, row 3608: A129608, row 3613: A072796, row 65352: A074680, row 79361: A123715.
See also tables A089840, A122200, A122201-A122204, A122283-A122284, A122285-A122288, A122289-A122290.

Programs

  • Scheme
    (define (SPINE foo) (letrec ((bar (lambda (s) (let ((t (foo s))) (if (pair? t) (cons (car t) (bar (cdr t))) t))))) bar))
(define (!SPINE foo!) (letrec ((bar! (lambda (s) (cond ((pair? s) (foo! s) (bar! (cdr s)))) s))) bar!))

A127302 Matula-Goebel signatures for plane binary trees encoded by A014486.

Original entry on oeis.org

1, 4, 14, 14, 86, 86, 49, 86, 86, 886, 886, 454, 886, 886, 301, 301, 301, 886, 886, 301, 454, 886, 886, 13766, 13766, 6418, 13766, 13766, 3986, 3986, 3986, 13766, 13766, 3986, 6418, 13766, 13766, 3101, 3101, 1589, 3101, 3101, 1849, 1849, 3101, 13766
Offset: 0

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Author

Antti Karttunen, Jan 16 2007

Keywords

Comments

This sequence maps A000108(n) oriented (plane) rooted binary trees encoded in range [A014137(n-1)..A014138(n-1)] of A014486 to A001190(n+1) non-oriented rooted binary trees, encoded by their Matula-Goebel numbers (when viewed as a subset of non-oriented rooted general trees). See also the comments at A127301.
If the signature-permutation of a Catalan automorphism SP satisfies the condition A127302(SP(n)) = A127302(n) for all n, then it preserves the non-oriented form of a binary tree. Examples of such automorphisms include A069770, A057163, A122351, A069767/A069768, A073286-A073289, A089854, A089859/A089863, A089864, A122282, A123492-A123494, A123715/A123716, A127377-A127380, A127387 and A127388.
A153835 divides natural numbers to same equivalence classes, i.e. a(i) = a(j) <=> A153835(i) = A153835(j) - Antti Karttunen, Jan 03 2013

Examples

			A001190(n+1) distinct values occur each range [A014137(n-1)..A014138(n-1)]. As an example, terms A014486(4..8) encode the following five plane binary trees:
........\/.....\/.................\/.....\/...
.......\/.......\/.....\/.\/.....\/.......\/..
......\/.......\/.......\_/.......\/.......\/.
n=.....4........5........6........7........8..
The trees in positions 4, 5, 7 and 8 all produce Matula-Goebel number A000040(1)*A000040(A000040(1)*A000040(A000040(1)*A000040(1))) = 2*A000040(2*A000040(2*2)) = 2*A000040(14) = 2*43 = 86, as they are just different planar representations of the one and same non-oriented tree. The tree in position 6 produces Matula-Goebel number A000040(A000040(1)*A000040(1)) * A000040(A000040(1)*A000040(1)) = A000040(2*2) * A000040(2*2) = 7*7 = 49. Thus a(4..8) = 86,86,49,86,86.

Links

Crossrefs

Cf A127301, A153835, A153829.

Formula

a(n) = A127301(A057123(n)).
Can be also computed directly as a fold, see the Scheme-program. - Antti Karttunen, Jan 03 2013

A123492 An involution of nonnegative integers: signature permutation of a nonrecursive Catalan automorphism which swaps the sides of a binary tree if the left subtree of either the left or right hand side toplevel subtree is not empty and otherwise keeps the binary tree intact.

Original entry on oeis.org

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

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Author

Antti Karttunen, Oct 11 2006

Keywords

Comments

This automorphism effects the following transformation on the unlabeled rooted plane binary trees (letters A, B, C and D refer to arbitrary subtrees located on those nodes.)
.....B...C.....B...C...........A...B.............A...B...
......\./.......\./.............\./...............\./....
.......x...D.....x...D...........x...C.............x...C.
........\./.......\./.............\./...............\./..
.....A...x...-->...x...A...........x...D...-->...D...x...
......\./...........\./.............\./...........\./....
.......x.............x...............x.............x.....

Links

Crossrefs

Row 79361 of A089840. Used to construct A123493, A123494, A123715 and A123716. Cf. A069770.

A123494 Signature permutation of a Catalan automorphism: row 79361 of table A122202.

Original entry on oeis.org

0, 1, 2, 3, 4, 8, 6, 7, 5, 9, 22, 20, 21, 10, 14, 19, 16, 17, 13, 15, 11, 12, 18, 23, 64, 62, 63, 24, 54, 61, 57, 58, 27, 55, 25, 26, 59, 37, 60, 53, 56, 38, 42, 51, 44, 45, 36, 41, 34, 35, 46, 43, 52, 39, 28, 33, 40, 30, 31, 50, 47, 29, 48, 49, 32, 65, 196, 194, 195, 66
Offset: 0

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Author

Antti Karttunen, Oct 11 2006

Keywords

Comments

This is the signature-permutation of Catalan automorphism which is derived from the automorphism *A123492 with the recursion schema KROF (defined in A122202). Like automorphisms *A057163 and *A069767/*A069768 these automorphisms are closed with respect to the subset of "zigzagging" binary trees (i.e., those binary trees where there are no nodes with two nonempty branches, or equivalently, those ones for which Stanley's interpretation (c) forms a non-branching line) and thus induce a permutation of binary strings. That is, starting from the root of such a binary tree, the turns taken by nonempty branches are interpreted as binary digits 0 or 1, depending on whether the tree grows to the left or right. In this manner, the Catalan automorphisms *A123494 and *A123493 induce the Binary Reflected Gray Code (see A003188 and A006068).

Links

Crossrefs

Inverse: A123493. Row 79361 of A122202. See also A123715 and A123716.

A123716 Signature permutation of a Catalan automorphism: row 79361 of table A122204.

Original entry on oeis.org

0, 1, 2, 3, 4, 8, 6, 7, 5, 9, 22, 20, 21, 10, 14, 19, 16, 17, 18, 15, 11, 12, 13, 23, 64, 62, 63, 24, 54, 61, 57, 58, 59, 55, 25, 26, 27, 37, 60, 53, 56, 38, 42, 51, 44, 45, 46, 47, 48, 49, 50, 43, 52, 39, 28, 29, 40, 30, 31, 32, 41, 33, 34, 35, 36, 65, 196, 194, 195, 66
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 *A123492 with the recursion schema ENIPS (defined in A122204).

Links

Crossrefs

Inverse: A123715. Row 79361 of A122204.
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