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.

Previous Showing 21-30 of 125 results. Next

A277537 A(n,k) is the n-th derivative of the k-th tetration of x (power tower of order k) x^^k at x=1; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 2, 0, 0, 1, 1, 2, 3, 0, 0, 1, 1, 2, 9, 8, 0, 0, 1, 1, 2, 9, 32, 10, 0, 0, 1, 1, 2, 9, 56, 180, 54, 0, 0, 1, 1, 2, 9, 56, 360, 954, -42, 0, 0, 1, 1, 2, 9, 56, 480, 2934, 6524, 944, 0, 0, 1, 1, 2, 9, 56, 480, 4374, 26054, 45016, -5112, 0, 0
Offset: 0

Views

Author

Alois P. Heinz, Oct 19 2016

Keywords

Examples

			Square array A(n,k) begins:
  1, 1,   1,    1,     1,     1,     1,     1, ...
  0, 1,   1,    1,     1,     1,     1,     1, ...
  0, 0,   2,    2,     2,     2,     2,     2, ...
  0, 0,   3,    9,     9,     9,     9,     9, ...
  0, 0,   8,   32,    56,    56,    56,    56, ...
  0, 0,  10,  180,   360,   480,   480,   480, ...
  0, 0,  54,  954,  2934,  4374,  5094,  5094, ...
  0, 0, -42, 6524, 26054, 47894, 60494, 65534, ...
		

Crossrefs

Rows n=0..1 give A000012, A057427.
Main diagonal gives A033917.

Programs

  • Maple
    f:= proc(n) f(n):= `if`(n=0, 1, (x+1)^f(n-1)) end:
    A:= (n, k)-> n!*coeff(series(f(k), x, n+1), x, n):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
    # second Maple program:
    b:= proc(n, k) option remember; `if`(n=0, 1, `if`(k=0, 0,
          -add(binomial(n-1, j)*b(j, k)*add(binomial(n-j, i)*
          (-1)^i*b(n-j-i, k-1)*(i-1)!, i=1..n-j), j=0..n-1)))
        end:
    A:= (n, k)-> b(n, min(k, n)):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    b[n_, k_] := b[n, k] = If[n==0, 1, If[k==0, 0, -Sum[Binomial[n-1, j]*b[j, k]*Sum[Binomial[n-j, i]*(-1)^i*b[n-j-i, k-1]*(i-1)!, {i, 1, n-j}], {j, 0, n-1}]]]; A[n_, k_] := b[n, Min[k, n]]; Table[A[n, d-n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, Jan 14 2017, adapted from 2nd Maple prog. *)

Formula

A(n,k) = [(d/dx)^n x^^k]_{x=1}.
E.g.f. of column k: (x+1)^^k.
A(n,k) = Sum_{i=0..min(n,k)} A277536(n,i).
A(n,k) = n * A295028(n,k) for n,k > 0.

A089858 Permutation of natural numbers induced by Catalan Automorphism *A089858 acting on the binary trees/parenthesizations encoded by A014486/A063171.

Original entry on oeis.org

0, 1, 3, 2, 6, 8, 7, 4, 5, 14, 15, 19, 21, 22, 16, 20, 17, 9, 10, 18, 11, 12, 13, 37, 38, 39, 40, 41, 51, 52, 56, 58, 59, 60, 62, 63, 64, 42, 43, 53, 57, 61, 44, 54, 45, 23, 24, 46, 25, 26, 27, 47, 55, 48, 28, 29, 49, 30, 31, 32, 50, 33, 34, 35, 36, 107, 108, 109, 110, 111
Offset: 0

Views

Author

Antti Karttunen, Nov 29 2003

Keywords

Comments

This automorphism effects the following transformation on the unlabeled rooted plane binary trees (letters A, B, C refer to arbitrary subtrees located on those nodes and () stands for an implied terminal node.)
.....B...C.......B...A
......\./.........\./
...A...x...-->... .x...C...............A..().........()..A..
....\./.............\./.................\./....-->....\./...
.....x...............x...................x.............x....
((a . b) . c) -> ((b . a) . c) ____ (a . ()) ---> (() . a)
See the Karttunen OEIS-Wiki link for a detailed explanation how to obtain a given integer sequence from this definition.

Crossrefs

Row 13 of A089840. Inverse of A089861. a(n) = A072797(A069770(n)) = A069770(A089852(n)) = A057163(A073270(A057163(n))).
Number of cycles: A073193. Number of fixed-points: A019590. Max. cycle size: A089422. LCM of cycle sizes: A089423 (in each range limited by A014137 and A014138).

Extensions

Further comments and constructive implementation of Scheme-function (*A089858) added by Antti Karttunen, Jun 04 2011

A089860 Permutation of natural numbers induced by Catalan automorphism *A089860 acting on the binary trees/parenthesizations encoded by A014486/A063171.

Original entry on oeis.org

0, 1, 3, 2, 8, 6, 7, 4, 5, 21, 22, 19, 14, 15, 20, 16, 17, 9, 10, 18, 11, 12, 13, 58, 59, 62, 63, 64, 56, 60, 51, 37, 38, 52, 39, 40, 41, 57, 61, 53, 42, 43, 54, 44, 45, 23, 24, 46, 25, 26, 27, 55, 47, 48, 28, 29, 49, 30, 31, 32, 50, 33, 34, 35, 36, 170, 171, 174, 175, 176, 184
Offset: 0

Views

Author

Antti Karttunen, Nov 29 2003

Keywords

Comments

This automorphism effects the following transformation on the unlabeled rooted plane binary trees (letters A, B, C refer to arbitrary subtrees located on those nodes and () stands for an implied terminal node).
.....B...C.......C...A
......\./.........\./
...A...x...-->... .x...B...............A..().........()..A..
....\./.............\./.................\./....-->....\./...
.....x...............x...................x.............x....
(a . (b . c)) --> ((c . a) . b) ___ (a . ()) --> (() . a)
See the Karttunen OEIS-Wiki link for a detailed explanation of how to obtain a given integer sequence from this definition.

Crossrefs

Row 16 of A089840. Inverse of A089862. a(n) = A089855(A069770(n)) = A069770(A089851(n)) = A069770(A074680(A069770(n))) = A057163(A089862(A057163(n))).
Number of cycles: A001683 (probably, not checked). Number of fixed points: A019590. Max. cycle size & LCM of all cycle sizes: A089410 (in each range limited by A014137 and A014138).

Extensions

A graphical description and constructive version of Scheme-implementation added by Antti Karttunen, Jun 04 2011

A089861 Permutation of natural numbers induced by Catalan Automorphism *A089861 acting on the binary trees/parenthesizations encoded by A014486/A063171.

Original entry on oeis.org

0, 1, 3, 2, 7, 8, 4, 6, 5, 17, 18, 20, 21, 22, 9, 10, 14, 16, 19, 11, 15, 12, 13, 45, 46, 48, 49, 50, 54, 55, 57, 58, 59, 61, 62, 63, 64, 23, 24, 25, 26, 27, 37, 38, 42, 44, 47, 51, 53, 56, 60, 28, 29, 39, 43, 52, 30, 40, 31, 32, 33, 41, 34, 35, 36, 129, 130, 132, 133, 134, 138
Offset: 0

Views

Author

Antti Karttunen, Nov 29 2003

Keywords

Comments

This automorphism effects the following transformation on the unlabeled rooted plane binary trees (letters A, B, C refer to arbitrary subtrees located on those nodes and () stands for an implied terminal node).
.A...B...............A...C
..\./.................\./
...x...C...-->.....B...x...............()..A.........A..()..
....\./.............\./.................\./....-->....\./...
.....x...............x...................x.............x....
((a . b) . c) --> (b . (a . c)) __ (() . a) ----> (a . ())
See the Karttunen OEIS-Wiki link for a detailed explanation of how to obtain a given integer sequence from this definition.

Crossrefs

Row 18 of A089840. Inverse of A089858. a(n) = A089852(A069770(n)) = A069770(A072797(n)) = A057163(A073269(A057163(n))).
Number of cycles: A073193. Number of fixed-points: A019590. Max. cycle size: A089422. LCM of cycle sizes: A089423 (in each range limited by A014137 and A014138).

Extensions

A graphical description and constructive version of Scheme-implementation added by Antti Karttunen, Jun 04 2011

A089862 Permutation of natural numbers induced by Catalan automorphism *A089862 acting on the binary trees/parenthesizations encoded by A014486/A063171.

Original entry on oeis.org

0, 1, 3, 2, 7, 8, 5, 6, 4, 17, 18, 20, 21, 22, 12, 13, 15, 16, 19, 11, 14, 9, 10, 45, 46, 48, 49, 50, 54, 55, 57, 58, 59, 61, 62, 63, 64, 31, 32, 34, 35, 36, 40, 41, 43, 44, 47, 52, 53, 56, 60, 30, 33, 39, 42, 51, 28, 37, 23, 24, 29, 38, 25, 26, 27, 129, 130, 132, 133, 134
Offset: 0

Views

Author

Antti Karttunen, Nov 29 2003

Keywords

Comments

This automorphism effects the following transformation on the unlabeled rooted plane binary trees (letters A, B, C refer to arbitrary subtrees located on those nodes and () stands for an implied terminal node).
.A...B...............C...A
..\./.................\./
...x...C...-->.....B...x...............()..A.........A..()..
....\./.............\./.................\./....-->....\./...
.....x...............x...................x.............x....
((a . b) . c) --> (b . (c . a)) __ (() . a) ----> (a . ())
See the Karttunen OEIS-Wiki link for a detailed explanation of how to obtain a given integer sequence from this definition.

Crossrefs

Row 20 of A089840. Inverse of A089860. a(n) = A089853(A069770(n)) = A069770(A089857(n)) = A069770(A074679(A069770(n))) = A057163(A089860(A057163(n))). Number of cycles: A001683 (seems to be, not checked). Number of fixed points: A019590. Max. cycle size & LCM of all cycle sizes: A089410 (in each range limited by A014137 and A014138).

Extensions

A graphical description and constructive version of Scheme-implementation added by Antti Karttunen, Jun 04 2011

A304182 Number of primitive inequivalent mirror-symmetric sublattices of rectangular lattice of index n.

Original entry on oeis.org

1, 3, 2, 4, 2, 6, 2, 4, 2, 6, 2, 8, 2, 6, 4, 4, 2, 6, 2, 8, 4, 6, 2, 8, 2, 6, 2, 8, 2, 12, 2, 4, 4, 6, 4, 8, 2, 6, 4, 8, 2, 12, 2, 8, 4, 6, 2, 8, 2, 6, 4, 8, 2, 6, 4, 8, 4, 6, 2, 16, 2, 6, 4, 4, 4, 12, 2, 8, 4, 12, 2, 8, 2, 6, 4, 8, 4, 12, 2, 8, 2, 6, 2, 16, 4
Offset: 1

Views

Author

Andrey Zabolotskiy, May 07 2018

Keywords

Examples

			There are 6 = A001615(4) lattices in Z^2 whose quotient group is C_4. The reflection through an axis relates <(4,0), (1,1)> and <(4,0), (3,1)>. The remaining 4 = a(4) lattices are fixed.
		

Crossrefs

Cf. A069735 (not only primitive sublattices), A304183 (primitive oblique sublattices), A069734 (all sublattices).
Cf. other columns of tables 4 and 5 from [Rutherford, 2009]: A001615, A060594, A157223, A000089, A157224, A000086, A157227, A019590, A157228, A157226, A157230, A157231, A154272, A157235.

Programs

  • Mathematica
    f[p_, e_] := If[p == 2, If[e == 1, 3, 4], 2]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Oct 22 2022 *)

Formula

From Álvar Ibeas, Mar 18 2021: (Start)
For n odd, a(n) = A034444(n) = 2^(A001221(n)).
For n even, a(n) = A034444(n) + A034444(n/2). If 4|n, a(n) = 2^(A001221(n) + 1); otherwise, a(n) = 3 * 2^(A001221(n) - 1).
Multiplicative with a(2) = 3, a(2^e) = 4 (for e>1), and a(p^e) = 2 (for p>2).
Dirichlet g.f.: (1+2^(-s)) * zeta(s)^2 / zeta(2s).
(End)
Sum_{k=1..n} a(k) ~ (log(n) + 2*gamma - log(2)/3 - 2*zeta'(2)/zeta(2) - 1)*9*n/Pi^2, where gamma is Euler's constant (A001620). - Amiram Eldar, Dec 31 2022

A273693 Number A(n,k) of k-ary heaps on n elements; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 2, 1, 0, 1, 1, 1, 2, 3, 1, 0, 1, 1, 1, 2, 6, 8, 1, 0, 1, 1, 1, 2, 6, 12, 20, 1, 0, 1, 1, 1, 2, 6, 24, 40, 80, 1, 0, 1, 1, 1, 2, 6, 24, 60, 180, 210, 1, 0, 1, 1, 1, 2, 6, 24, 120, 240, 630, 896, 1, 0, 1, 1, 1, 2, 6, 24, 120, 360, 1260, 3360, 3360, 1, 0
Offset: 0

Views

Author

Alois P. Heinz, May 28 2016

Keywords

Examples

			A(4,2) = 3: 1234, 1243, 1324.
A(5,2) = 8: 12345, 12354, 12435, 12453, 12534, 12543, 13245, 13254.
A(5,3) = 12: 12345, 12354, 12435, 12453, 12534, 12543, 13245, 13254, 13425, 13524, 14235, 14325.
A(6,3) = 40: 123456, 123465, 123546, 123564, 123645, 123654, 124356, 124365, 124536, 124563, 124635, 124653, 125346, 125364, 125436, 125463, 125634, 125643, 126345, 126354, 126435, 126453, 126534, 126543, 132456, 132465, 132546, 132564, 132645, 132654, 134256, 134265, 135246, 135264, 136245, 136254, 142356, 142365, 143256, 143265.
(The examples use min-heaps.)
Square array A(n,k) begins:
  1, 1,   1,   1,    1,    1,    1,    1, ...
  1, 1,   1,   1,    1,    1,    1,    1, ...
  0, 1,   1,   1,    1,    1,    1,    1, ...
  0, 1,   2,   2,    2,    2,    2,    2, ...
  0, 1,   3,   6,    6,    6,    6,    6, ...
  0, 1,   8,  12,   24,   24,   24,   24, ...
  0, 1,  20,  40,   60,  120,  120,  120, ...
  0, 1,  80, 180,  240,  360,  720,  720, ...
  0, 1, 210, 630, 1260, 1680, 2520, 5040, ...
		

Crossrefs

Main diagonal gives: A000142(n-1) for n>0.
Cf. A273712.

Programs

  • Maple
    with(combinat):
    A:= proc(n, k) option remember; local h, i, x, y, z;
          if n<2 then 1 elif k<2 then k
        else h:= ilog[k]((k-1)*n+1);
             if k^h=(k-1)*n+1 then A((n-1)/k, k)^k*
                multinomial(n-1, ((n-1)/k)$k)
           else x, y:=(k^h-1)/(k-1), (k^(h-1)-1)/(k-1);
                for i from 0 do z:= (n-1)-(k-1-i)*y-i*x;
                  if y<=z and z<=x then A(y, k)^(k-1-i)*
                     multinomial(n-1, y$(k-1-i), x$i, z)*
                     A(x, k)^i*A(z, k); break fi
                od
          fi fi
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    multinomial[n_, k_] := n!/Times @@ (k!); A[n_, k_] := A[n, k] = Module[{h, i, x, y, z}, Which[n<2, 1, k<2, k, True, h = Floor @ Log[k, (k-1)*n+1]; If[k^h == (k-1)*n+1, A[(n-1)/k, k]^k*multinomial[n-1, Array[((n-1)/k)&, k]], {x, y} = {(k^h-1)/(k-1), (k^(h-1)-1)/(k-1)}; For[i = 0, True, i++, z = (n-1)-(k-1-i)*y-i*x; If[y<=z && z<=x, A[y, k]^(k-1-i)*multinomial[n-1, Join[Array[y&, k-1-i], Array[x&, i], {z}]]*A[x, k]^i*A[z, k] // Return]] ]]]; Table[A[n, d-n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, Mar 13 2017, translated from Maple *)

A373451 Number T(n,k) of (binary) heaps of length n whose element set equals [k]; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 3, 2, 0, 1, 5, 7, 3, 0, 1, 9, 23, 23, 8, 0, 1, 14, 55, 92, 70, 20, 0, 1, 24, 147, 386, 502, 320, 80, 0, 1, 34, 281, 1004, 1861, 1880, 985, 210, 0, 1, 54, 633, 3128, 8113, 12008, 10237, 4690, 896, 0, 1, 79, 1241, 8039, 27456, 54900, 66730, 48650, 19600, 3360
Offset: 0

Views

Author

Alois P. Heinz, Jun 05 2024

Keywords

Comments

These heaps may contain repeated elements. Their element sets are gap-free and contain 1 (if nonempty).
T(n,k) is defined for n,k >= 0. The triangle contains only the terms with k<=n. T(n,k) = 0 for k>n.

Examples

			T(4,1) = 1: 1111.
T(4,2) = 5: 2111, 2121, 2211, 2212, 2221.
T(4,3) = 7: 3121, 3211, 3212, 3221, 3231, 3312, 3321.
T(4,4) = 3: 4231, 4312, 4321.
(The examples use max-heaps.)
Triangle T(n,k) begins:
  1;
  0, 1;
  0, 1,  1;
  0, 1,  3,   2;
  0, 1,  5,   7,    3;
  0, 1,  9,  23,   23,    8;
  0, 1, 14,  55,   92,   70,    20;
  0, 1, 24, 147,  386,  502,   320,    80;
  0, 1, 34, 281, 1004, 1861,  1880,   985,  210;
  0, 1, 54, 633, 3128, 8113, 12008, 10237, 4690, 896;
  ...
		

Crossrefs

Columns k=0-4 give A000007, A057427, A091980(n+1)-2, A376962, A376963.
Row sums give A373452.
Row maxima give A373608.
Main diagonal gives A056971.
First lower diagonal gives A373496.
T(2n,n) gives A373500.
Antidiagonal sums give A373632.
Antidiagonal maxima give A373897.

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(n=0, 1,
         (g-> (f-> add(b(f, j)*b(n-1-f, j), j=1..k)
                 )(min(g-1, n-g/2)))(2^ilog2(n)))
        end:
    T:= (n, k)-> add(binomial(k, j)*(-1)^j*b(n, k-j), j=0..k):
    seq(seq(T(n, k), k=0..n), n=0..12);
  • Mathematica
    b[n_, k_] := b[n, k] = If[n == 0, 1,
       Function[g, Function[f, Sum[b[f, j]*b[n-1-f, j], {j, 1, k}]][
          Min[g-1, n-g/2]]][2^(Length@IntegerDigits[n, 2]-1)]];
    T[n_, k_] := Sum[Binomial[k, j]*(-1)^j*b[n, k-j], {j, 0, k}];
    Table[Table[T[n, k], {k, 0, n}], {n, 0, 12}] // Flatten (* Jean-François Alcover, Sep 20 2024, after Alois P. Heinz *)

Formula

T(n,k) = Sum_{j=0..k} binomial(k,j) * (-1)^j * A373449(n,k-j).
Sum_{k=0..n} (-1)^k * T(n,n-k) = A019590(n+1).

A049403 A triangle of numbers related to triangle A030528; array a(n,m), read by rows (1 <= m <= n).

Original entry on oeis.org

1, 1, 1, 0, 3, 1, 0, 3, 6, 1, 0, 0, 15, 10, 1, 0, 0, 15, 45, 15, 1, 0, 0, 0, 105, 105, 21, 1, 0, 0, 0, 105, 420, 210, 28, 1, 0, 0, 0, 0, 945, 1260, 378, 36, 1, 0, 0, 0, 0, 945, 4725, 3150, 630, 45, 1, 0, 0, 0, 0, 0, 10395, 17325, 6930, 990, 55, 1, 0, 0, 0, 0, 0, 10395, 62370
Offset: 1

Views

Author

Keywords

Comments

a(n,1) = A019590(n) = A008279(1,n). a(n,m) =: S1(-1; n,m), a member of a sequence of lower triangular Jabotinsky matrices, including S1(1; n,m) = A008275 (signed Stirling first kind), S1(2; n,m) = A008297(n,m) (signed Lah numbers). a(n,m) matrix is inverse to signed matrix ((-1)^(n-m))*A001497(n-1,m-1) (signed Bessel triangle). The monic row polynomials E(n,x) := Sum_{m=1..n} a(n,m)*x^m, E(0,x) := 1 are exponential convolution polynomials (see A039692 for the definition and a Knuth reference).
Exponential Riordan array [1+x, x(1+x/2)]. T(n,k) = A001498(k+1, n-k). - Paul Barry, Jan 15 2009

Examples

			Triangle a(n,m) (with rows n >= 1 and columns m >= 1) begins as follows:
  1;                 with row polynomial E(1,x) = x;
  1, 1;              with row polynomial E(2,x) = x^2 + x;
  0, 3,  1;          with row polynomial E(3,x) = 3*x^2 + x^3;
  0, 3,  6,   1;     with row polynomial E(4,x) = 3*x^2 + 6*x^3 + x^4;
  0, 0, 15,  10,   1;
  0, 0, 15,  45,  15,   1;
  0, 0,  0, 105, 105,  21,  1;
  0, 0,  0, 105, 420, 210, 28, 1;
  ...
		

Crossrefs

Variations of this array: A096713, A104556, A122848, A130757.

Programs

  • Maple
    # The function BellMatrix is defined in A264428.
    # Adds (1,0,0,0, ..) as column 0.
    BellMatrix(n -> `if`(n<2,1,0), 9); # Peter Luschny, Jan 28 2016
  • Mathematica
    t[n_, k_] := k!*Binomial[n, k]/((2 k - n)!*2^(n - k)); Table[ t[n, k], {n, 11}, {k, n}] // Flatten
    (* Second program: *)
    BellMatrix[f_Function, len_] := With[{t = Array[f, len, 0]}, Table[BellY[n, k, t], {n, 0, len-1}, {k, 0, len-1}]];
    rows = 13;
    M = BellMatrix[If[#<2, 1, 0]&, rows];
    Table[M[[n, k]], {n, 2, rows}, {k, 2, n}] // Flatten (* Jean-François Alcover, Jun 23 2018, after Peter Luschny *)

Formula

a(n, m) = n!*A030528(n, m)/(m!*2^(n-m)) for n >= m >= 1.
a(n, m) = (2*m-n+1)*a(n-1, m) + a(n-1, m-1) for n >= m >= 1 with a(n, m) = 0 for n < m, a(n, 0) := 0, and a(1, 1) = 1. [The 0th column does not appear in this array. - Petros Hadjicostas, Oct 28 2019]
E.g.f. for the m-th column: (x*(1 + x/2))^m/m!.
a(n,m) = A122848(n,m). - R. J. Mathar, Jan 14 2011

A057503 Signature-permutation of a Catalan Automorphism: Deutsch's 1998 bijection on Dyck paths.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Sep 03 2000

Keywords

Comments

Deutsch shows in his 1998 paper that this automorphism maps the number of returns of Dyck path to the height of the last peak, i.e., that A057515(n) = A080237(A057503(n)) holds for all n, thus the two parameters have the same distribution.
From the recursive forms of A057161 and A057503 it is seen that both can be viewed as a convergent limits of a process where either the left or right side argument of A085201 in formula for A057501 is "iteratively recursivized", and on the other hand, both of these can then in turn be made to converge towards A057505, when the other side of the formula is also "recursivized" in the same way. - Antti Karttunen, Jun 06 2014

Crossrefs

Inverse: A057504. Row 17 of A122285. Cf. A057501, A057161, A057505.
The number of cycles, count of the fixed points, maximum cycle sizes and LCM's of all cycle sizes in range [A014137(n-1)..A014138(n)] of this permutation are given by LEFT(LEFT(A001683)), LEFT(A019590), A057544 and A057544, the same sequences as for A057162 because this is a conjugate of it (cf. the Formula section).

Formula

a(0) = 0, and for n >= 1, a(n) = A085201(A072771(n), A057548(a(A072772(n)))). [This formula 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 the unary form of function 'list'].
a(n) = A057164(A057162(A057164(n))). [For the proof, see pp. 53-54 in the "Introductory survey ..." draft, eq. 144.]
Other identities:
A057515(n) = A080237(a(n)) holds for all n. [See the Comments section.]

Extensions

Equivalence with Emeric Deutsch's 1998 bijection realized Dec 15 2006 and entry edited accordingly by Antti Karttunen, Jan 16 2007
Previous Showing 21-30 of 125 results. Next