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 1-7 of 7 results.

A080977 a(n) = A080272(2*n)/A080292(n).

Original entry on oeis.org

1, 1, 6, 2, 14, 14, 22, 22, 18, 18, 46, 46, 62, 62, 26, 26
Offset: 0

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Author

Antti Karttunen, Mar 02 2003

Keywords

Comments

This gives the orbit size (under the Catalan bijection A057505) for every other binomial-mod-2 tree A080263(2*n) divided by the orbit size of the corresponding branch-reduced tree A080293(n). See comment at A080972.

A080302 a(n) = A080292(n)/3.

Original entry on oeis.org

1, 3, 3, 27, 27, 27, 9, 567, 567, 567, 567, 891, 891, 297, 297
Offset: 1

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Author

Antti Karttunen, Mar 02 2003

Keywords

A057505 Signature-permutation of a Catalan Automorphism: Donaghey's map M acting on the parenthesizations encoded by A014486.

Original entry on oeis.org

0, 1, 3, 2, 8, 7, 5, 6, 4, 22, 21, 18, 20, 17, 13, 12, 15, 19, 16, 10, 11, 14, 9, 64, 63, 59, 62, 58, 50, 49, 55, 61, 57, 46, 48, 54, 45, 36, 35, 32, 34, 31, 41, 40, 52, 60, 56, 43, 47, 53, 44, 27, 26, 29, 33, 30, 38, 39, 51, 42, 24, 25, 28, 37, 23, 196, 195, 190, 194, 189
Offset: 0

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Author

Antti Karttunen, Sep 03 2000

Keywords

Comments

This is equivalent to map M given by Donaghey on page 81 of his paper "Automorphisms on ..." and also equivalent to the transformation procedure depicted in the picture (23) of Donaghey-Shapiro paper.
This can be also considered as a "more recursive" variant of A057501 or A057503 or A057161.

References

  • D. E. Knuth, The Art of Computer Programming, Volume 4, Fascicle 4: Generating All Trees--History of Combinatorial Generation, vi+120pp. ISBN 0-321-33570-8 Addison-Wesley Professional; 1ST edition (Feb 06, 2006).

Crossrefs

Inverse: A057506.
The 2nd, 3rd, 4th, 5th and 6th "power": A071661, A071663, A071665, A071667, A071669.
Other related permutations: A057501, A057503, A057161.
Cycle counts: A057507. Maximum cycle lengths: A057545. LCM's of all cycles: A060114. See A057501 for other Maple procedures.
Row 17 of table A122288.
Cf. A080981 (the "primitive elements" of this automorphism), A079438, A079440, A079442, A079444, A080967, A080968, A080972, A080272, A080292, A083929, A080973, A081164, A123050, A125977, A126312.

Programs

  • Maple
    map(CatalanRankGlobal,map(DonagheysM, A014486)); or map(CatalanRankGlobal,map(DeepRotateTriangularization, A014486));
    DonagheysM := n -> pars2binexp(DonagheysMP(binexp2pars(n)));
    DonagheysMP := h -> `if`((0 = nops(h)),h,[op(DonagheysMP(car(h))),DonagheysMP(cdr(h))]);
    DeepRotateTriangularization := proc(nn) local n,s,z,w; n := binrev(nn); z := 0; w := 0; while(1 = (n mod 2)) do s := DeepRotateTriangularization(BinTreeRightBranch(n))*2; z := z + (2^w)*s; w := w + binwidth(s); z := z + (2^w); w := w + 1; n := floor(n/2); od; RETURN(z); end;

Formula

a(0) = 0, and for n>=1, a(n) = A085201(a(A072771(n)), A057548(a(A072772(n)))). [This recurrence reflects the S-expression implementation given first in the Program section: A085201 is a 2-ary function corresponding to 'append', A072771 and A072772 correspond to 'car' and 'cdr' (known also as first/rest or head/tail in some languages), and A057548 corresponds to unary form of function 'list'].
As a composition of related permutations:
a(n) = A057164(A057163(n)).
a(n) = A057163(A057506(A057163(n))).

A080293 A014486-encoding of the branch-reduced binomial-mod-2 binary trees.

Original entry on oeis.org

2, 50, 14642, 3969842, 267572689202, 69427226972978, 4581045692538239282, 301220569271221714981682, 1295918094920364850246919050705202, 332029112115571675270693117549056818
Offset: 0

Views

Author

Antti Karttunen, Mar 02 2003

Keywords

Comments

These are obtained from the stunted binomial-mod-2 zigzag trees (A080263) either by extending each leaf to a branch of two leaves, or by branch-reducing every other such tree.

Crossrefs

a(n) = A014486(A080295(n)). Same sequence in binary: A080294. Breadth-first-wise encoding: A080318. "Moose-trees" obtained from these: A080973. Cf. A080292, A080297.

Formula

A080973 A014486-encoding of the "Moose trees".

Original entry on oeis.org

2, 52, 14952, 4007632, 268874213792, 68836555442592, 4561331969745081152, 300550070677246403229312, 1294530259719904904564091957759232, 331402554328705507772604330809117952
Offset: 0

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Author

Antti Karttunen, Mar 02 2003

Keywords

Comments

Meeussen's observation about the orbits of a composition of two involutions F and R states that if the orbit size of the composition (acting on a particular element of the set) is odd, then it contains an element fixed by the other involution if and only if it contains also an element fixed by the other, on the (almost) opposite side of the cycle. Here those two involutions are A057163 and A057164, their composition is Donaghey's "Map M" A057505 and as the trees A080293/A080295 are symmetric as binary trees and the cycle sizes A080292 are odd, it follows that these are symmetric as general trees.

Crossrefs

Same sequence in binary: A080974. A036044(a(n)) = a(n) for all n. The number of edges (as general trees): A080978.

Formula

a(n) = A014486(A080975(n)) = A014486(A057505^((A080292(n)+1)/2) (A080293(n))) [where ^ stands for the repeated applications of permutation A057505.]

A080272 Orbit size of each tree A080263(n) under Donaghey's "Map M" Catalan automorphism.

Original entry on oeis.org

1, 3, 3, 27, 54, 54, 18, 1134, 1134, 1134, 1134, 1782, 1782, 594, 594, 30618, 30618, 30618, 30618, 78246, 78246, 78246, 78246, 165726, 165726
Offset: 0

Views

Author

Antti Karttunen, Mar 02 2003

Keywords

Comments

This is the size of the cycle containing A080265(n) in the permutations A057505/A057506.

Crossrefs

A080977(n) = a(2*n)/A080292(n).

Formula

a(n) = A080967(A080265(n)).

A080975 A014486-index of the "Moose trees".

Original entry on oeis.org

1, 7, 515, 73211, 2249220471, 431283926958, 18838905762720934, 896134321804401371660, 2333852111980919691995847581921, 537961368577436933017494169487235
Offset: 0

Views

Author

Antti Karttunen, Mar 02 2003

Keywords

Comments

See A080973 for illustration and comments.

Crossrefs

A057164(a(n)) = a(n) for all n. Cf. A080976.

Formula

a(n) = A057505^((A080292(n)+1)/2) (A080293(n)) [where ^ stands for the repeated applications of permutation A057505.]
Showing 1-7 of 7 results.