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 1-10 of 19 results. Next

A215703 A(n,k) is the n-th derivative of f_k at x=1, and f_k is the k-th of all functions that are representable as x^x^...^x with m>=1 x's and parentheses inserted in all possible ways; square array A(n,k), n>=0, k>=1, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 0, 1, 1, 2, 0, 1, 1, 4, 3, 0, 1, 1, 2, 12, 8, 0, 1, 1, 6, 9, 52, 10, 0, 1, 1, 4, 27, 32, 240, 54, 0, 1, 1, 2, 18, 156, 180, 1188, -42, 0, 1, 1, 2, 15, 100, 1110, 954, 6804, 944, 0, 1, 1, 8, 9, 80, 650, 8322, 6524, 38960, -5112, 0, 1, 1, 6, 48, 56, 590, 4908, 70098, 45016, 253296, 47160, 0
Offset: 0

Views

Author

Alois P. Heinz, Aug 21 2012

Keywords

Comments

A000081(m) distinct functions are representable as x^x^...^x with m>=1 x's and parentheses inserted in all possible ways. Some functions are representable in more than one way, the number of valid parenthesizations is A000108(m-1). The f_k are ordered, such that the number m of x's in f_k is a nondecreasing function of k. The exact ordering is defined by the algorithm below.
The list of functions f_1, f_2, ... begins:
| f_k : m : function (tree) : representation(s) : sequence |
+-----+---+------------------+--------------------------+----------+
| f_1 | 1 | x -> x | x | A019590 |
| f_2 | 2 | x -> x^x | x^x | A005727 |
| f_3 | 3 | x -> x^(x*x) | (x^x)^x | A215524 |
| f_4 | 3 | x -> x^(x^x) | x^(x^x) | A179230 |
| f_5 | 4 | x -> x^(x*x*x) | ((x^x)^x)^x | A215704 |
| f_6 | 4 | x -> x^(x^x*x) | (x^x)^(x^x), (x^(x^x))^x | A215522 |
| f_7 | 4 | x -> x^(x^(x*x)) | x^((x^x)^x) | A215705 |
| f_8 | 4 | x -> x^(x^(x^x)) | x^(x^(x^x)) | A179405 |

Examples

			Square array A(n,k) begins:
  1,   1,    1,    1,     1,     1,     1,     1, ...
  1,   1,    1,    1,     1,     1,     1,     1, ...
  0,   2,    4,    2,     6,     4,     2,     2, ...
  0,   3,   12,    9,    27,    18,    15,     9, ...
  0,   8,   52,   32,   156,   100,    80,    56, ...
  0,  10,  240,  180,  1110,   650,   590,   360, ...
  0,  54, 1188,  954,  8322,  4908,  5034,  2934, ...
  0, -42, 6804, 6524, 70098, 41090, 47110, 26054, ...
		

Crossrefs

Programs

  • Maple
    T:= proc(n) T(n):=`if`(n=1, [x], map(h-> x^h, g(n-1$2))) end:
    g:= proc(n, i) option remember; `if`(i=1, [x^n], [seq(seq(
          seq(mul(T(i)[w[t]-t+1], t=1..j)*v, v=g(n-i*j, i-1)), w=
          combinat[choose]([$1..nops(T(i))+j-1], j)), j=0..n/i)])
        end:
    f:= proc() local i, l; i, l:= 0, []; proc(n) while n>
          nops(l) do i:= i+1; l:= [l[], T(i)[]] od; l[n] end
        end():
    A:= (n, k)-> n!*coeff(series(subs(x=x+1, f(k)), x, n+1), x, n):
    seq(seq(A(n, 1+d-n), n=0..d), d=0..12);
  • Mathematica
    T[n_] := If[n == 1, {x}, Map[x^#&, g[n - 1, n - 1]]];
    g[n_, i_] := g[n, i] = If[i == 1, {x^n}, Flatten @ Table[ Table[ Table[ Product[T[i][[w[[t]] - t + 1]], {t, 1, j}]*v, {v, g[n - i*j, i - 1]}], {w, Subsets[ Range[ Length[T[i]] + j - 1], {j}]}], {j, 0, n/i}]];
    f[n_] := Module[{i = 0, l = {}}, While[n > Length[l], i++; l = Join[l, T[i]]]; l[[n]]];
    A[n_, k_] := n! * SeriesCoefficient[f[k] /. x -> x+1, {x, 0, n}];
    Table[Table[A[n, 1+d-n], {n, 0, d}], {d, 0, 12}] // Flatten (* Jean-François Alcover, Nov 08 2019, after Alois P. Heinz *)

A179405 n-th derivative of x^(x^(x^x)) at x=1.

Original entry on oeis.org

1, 1, 2, 9, 56, 360, 2934, 26054, 269128, 3010680, 37616880, 504880992, 7387701672, 115228447152, 1929016301016, 34194883090440, 643667407174464, 12757366498618176, 266426229010029696, 5830527979298793024, 133665090871032478080, 3197905600674249843840
Offset: 0

Views

Author

Robert G. Wilson v, Jul 13 2010

Keywords

Comments

First term < 0: a(329). - Alois P. Heinz, Sep 22 2015

Crossrefs

Column k=8 of A215703.
Column k=4 of A277537.

Programs

  • Maple
    a:= n-> n!*coeff(series(subs(x=x+1, x^(x^(x^x)) ), x, n+1), x, n):
    seq(a(n), n=0..30);  # Alois P. Heinz, Aug 20 2012
  • Mathematica
    f[n_] := D[ x^(x^(x^x)), {x, n}] /. x -> 1; Array[f, 18, 0]
    Range[0, 21]! CoefficientList[ Series[(1 + x)^(1 + x)^(1 + x)^(1 + x), {x, 0, 21}], x] (* Robert G. Wilson v, Feb 03 2013 *)

Formula

E.g.f.: (x+1)^((x+1)^((x+1)^(x+1))). - Alois P. Heinz, Aug 23 2012

Extensions

a(18)-a(21) from Alois P. Heinz, Aug 20 2012

A215524 n-th derivative of (x^x)^x at x=1.

Original entry on oeis.org

1, 1, 4, 12, 52, 240, 1188, 6804, 38960, 253296, 1654560, 11816640, 85816608, 668005728, 5240582592, 44667645120, 365989405440, 3494595006720, 28075694694912, 325862541872640, 2101211758356480, 39605981661066240, 48568198208302080, 7549838510211486720, -66667098077331572736
Offset: 0

Views

Author

Alois P. Heinz, Aug 14 2012

Keywords

Crossrefs

Column k=3 of A215703.

Programs

  • Maple
    a:= n-> n!*coeff(series(subs(x=x+1, (x^x)^x ), x, n+1), x, n):
    seq(a(n), n=0..30);
  • Mathematica
    m = 24; CoefficientList[((x+1)^(x+1))^(x+1) + O[x]^(m+1), x]*Range[0, m]! (* Jean-François Alcover, Feb 07 2021 *)

Formula

E.g.f.: ((x+1)^(x+1))^(x+1).

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.

A215522 n-th derivative of (x^x)^(x^x) at x=1.

Original entry on oeis.org

1, 1, 4, 18, 100, 650, 4908, 41090, 382520, 3863808, 42409440, 497972112, 6259762320, 83343114504, 1175904241848, 17442325040520, 272149555445760, 4438451554802880, 75714874759039104, 1343817666163911168, 24837691533530152320, 475811860099666527360
Offset: 0

Views

Author

Alois P. Heinz, Aug 14 2012

Keywords

Comments

Also n-th derivative of (x^(x^x))^x = x^(x^x*x) at x=1.
First term < 0: a(65).

Crossrefs

Column k=6 of A215703.

Programs

  • Maple
    a:= n-> n!*coeff(series(subs(x=x+1, (x^x)^(x^x) ), x, n+1), x, n):
    seq(a(n), n=0..30);
  • Mathematica
    m = 21; CoefficientList[(x+1)^((x+1)^(x+2)) + O[x]^(m+1), x]*Range[0, m]! (* Jean-François Alcover, Feb 07 2021 *)

Formula

E.g.f.: (x+1)^((x+1)^(x+2)).

A179505 n-th derivative of x^(x^(x^(x^x))) at x=1.

Original entry on oeis.org

1, 1, 2, 9, 56, 480, 4374, 47894, 574888, 7829424, 116392080, 1901059512, 33564909432, 639562529424, 13047133134840, 283976169754440, 6563364026374464, 160538113862231808, 4141949353327046592, 112396373034208003008, 3199752121483607518080
Offset: 0

Views

Author

Robert G. Wilson v, Jul 17 2010

Keywords

Crossrefs

Column k=17 of A215703.
Column k=5 of A277537.

Programs

  • Maple
    a:= n-> n!*coeff(series(subs(x=x+1, x^(x^(x^(x^x))) ), x, n+1), x, n):
    seq(a(n), n=0..25);  # Alois P. Heinz, Aug 21 2012
  • Mathematica
    f[n_] := D[x^(x^(x^(x^x))), {x, n}] /. x -> 1; Array[f, 16, 0]
    Range[0, 20]! CoefficientList[ Series[(1 + x)^(1 + x)^(1 + x)^(1 + x)^(1 + x), {x, 0, 20}], x] (* Robert G. Wilson v, Feb 03 2013 *)

Formula

E.g.f.: (x+1)^((x+1)^((x+1)^((x+1)^(x+1)))). - Alois P. Heinz, Aug 21 2012

Extensions

a(16)-a(20) from Alois P. Heinz, Aug 21 2012

A215704 n-th derivative of ((x^x)^x)^x at x=1.

Original entry on oeis.org

1, 1, 6, 27, 156, 1110, 8322, 70098, 646272, 6333336, 66712680, 745731360, 8780828328, 108873486072, 1413807287760, 19157627737080, 270460073295360, 3965693824244160, 60266513065134528, 947644484349584448, 15389579447794454400, 257702782790624613120
Offset: 0

Views

Author

Alois P. Heinz, Aug 21 2012

Keywords

Comments

Also n-th derivative of x^(x^3) at x=1.
First term < 0: a(57).

Crossrefs

Column k=5 of A215703.

Programs

  • Maple
    a:= n-> n!*coeff(series(subs(x=x+1, ((x^x)^x)^x ), x, n+1), x, n):
    seq(a(n), n=0..25);

Formula

E.g.f.: (x+1)^((x+1)^3).

A211205 n-th derivative of x^(x^(x^(x^(x^x)))) at x=1.

Original entry on oeis.org

1, 1, 2, 9, 56, 480, 5094, 60494, 823528, 12365424, 206078880, 3745686912, 74083090872, 1579529362944, 36165466533000, 884104045301640, 22992315801392064, 633547543117707648, 18439576158792912192, 565162707747635408448, 18194047307015185486080
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Maple
    a:= n-> n!*coeff(series(subs(x=x+1, x^(x^(x^(x^(x^x))))), x, n+1), x, n):
    seq(a(n), n=0..20);
  • Mathematica
    NestList[ Factor[ D[#1, x]] &, x^x^x^x^x^x, 9] /. (x -> 1) (* or quicker *)
    Range[0, 20]! CoefficientList[ Series[(1 + x)^(1 + x)^(1 + x)^(1 + x)^(1 + x)^(1 + x), {x, 0, 20}], x]

Formula

E.g.f.: (x+1)^((x+1)^((x+1)^((x+1)^((x+1)^(x+1))))).

A215643 n-th derivative of x^((x^(x^x))^x) at x=1.

Original entry on oeis.org

1, 1, 2, 15, 104, 890, 8814, 100660, 1288048, 18337680, 286674960, 4882660464, 89880715704, 1777384045944, 37552294300416, 843830334815640, 20086549955304384, 504750167170162944, 13348550475903813120, 370499740676381737728, 10766442934111876381440
Offset: 0

Views

Author

Alois P. Heinz, Aug 18 2012

Keywords

Comments

Also n-th derivative of x^((x^x)^(x^x)) = x^(x^(x^x*x)) at x=1.

Crossrefs

Column k=15 of A215703.

Programs

  • Maple
    a:= n-> n!*coeff(series(subs(x=x+1, x^((x^(x^x))^x) ), x, n+1), x, n):
    seq(a(n), n=0..30);
  • Mathematica
    m = 20;
    CoefficientList[(x+1)^(((x+1)^((x+1)^(x+1)))^(x+1)) + O[x]^(m+1), x]* Range[0, m]! (* Jean-François Alcover, Feb 07 2021 *)

Formula

E.g.f.: (x+1)^(((x+1)^((x+1)^(x+1)))^(x+1)).

A215629 n-th derivative of x^(x^((x^x)^x)) at x=1.

Original entry on oeis.org

1, 1, 2, 9, 80, 660, 6714, 77084, 1005640, 14572944, 233086920, 4066783512, 76906345944, 1566049091568, 34153725715368, 793996577407560, 19595885746343808, 511550462381982528, 14080034085212120256, 407434430977558009344, 12363449947108075756800
Offset: 0

Views

Author

Alois P. Heinz, Aug 18 2012

Keywords

Crossrefs

Column k=16 of A215703.

Programs

  • Maple
    a:= n-> n!*coeff(series(subs(x=x+1, x^(x^((x^x)^x)) ), x, n+1), x, n):
    seq(a(n), n=0..30);
  • Mathematica
    m = 20;
    CoefficientList[(x+1)^((x+1)^(((x+1)^(x+1))^(x+1))) + O[x]^(m+1), x]* Range[0, m]! (* Jean-François Alcover, Feb 07 2021 *)

Formula

E.g.f: (x+1)^((x+1)^(((x+1)^(x+1))^(x+1))).
Showing 1-10 of 19 results. Next