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.

A039814 Matrix square of Stirling-1 triangle A008275.

Original entry on oeis.org

1, -2, 1, 7, -6, 1, -35, 40, -12, 1, 228, -315, 130, -20, 1, -1834, 2908, -1485, 320, -30, 1, 17582, -30989, 18508, -5005, 665, -42, 1, -195866, 375611, -253400, 81088, -13650, 1232, -56, 1, 2487832, -5112570, 3805723, -1389612, 279048, -32130, 2100, -72, 1
Offset: 1

Views

Author

Christian G. Bower, Feb 15 1999

Keywords

Comments

Exponential Riordan array [1/((1 + x)*(1 + log(1 + x))), log(1 + log(1 + x))]. The row sums of the unsigned array give A007840 (apart from the initial term). - Peter Bala, Jul 22 2014
Also the Bell transform of (-1)^n*A003713(n+1). For the definition of the Bell transform see A264428. - Peter Luschny, Jan 28 2016

Examples

			Triangle begins:
      1;
     -2,    1;
      7,   -6,     1;
    -35,   40,   -12,   1;
    228, -315,   130, -20,   1;
  -1834, 2908, -1485, 320, -30, 1;
...
		

Crossrefs

Column k=1..3 give (-1)^(n-1) * A003713(n), (-1)^n * A341587(n), (-1)^(n-1) * A341588(n).
Cf. A007840.

Programs

  • Maple
    # The function BellMatrix is defined in A264428.
    # Adds (1,0,0,0, ..) as column 0.
    BellMatrix(n -> (-1)^n*add(k!*abs(Stirling1(n+1,k+1)), k=0..n), 10); # Peter Luschny, Jan 28 2016
  • Mathematica
    max = 9; t = Table[StirlingS1[n, k], {n, 1, max}, {k, 1, max}]; t2 = t.t; Table[t2[[n, k]], {n, 1, max}, {k, 1, n}] // Flatten (* Jean-François Alcover, Feb 01 2013 *)
    rows = 9;
    t = Table[(-1)^n*Sum[k!*Abs[StirlingS1[n+1, k+1]], {k,0,n}], {n, 0, rows}];
    T[n_, k_] := BellY[n, k, t];
    Table[T[n, k], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 22 2018, after Peter Luschny *)
  • PARI
    T(n, k) = sum(j=0, n, stirling(n, j, 1)*stirling(j, k, 1)); \\ Seiichi Manyama, Feb 13 2022

Formula

E.g.f. of k-th column: ((log(1+log(1+x)))^k)/k!.
E.g.f.: 1/(1 + t)*( 1 + log(1 + t) )^(x-1) = 1 + (-2 + x)*t + (7 - 6*x + x^2)*t^2/2! + .... - Peter Bala, Jul 22 2014
T(n,k) = Sum_{j=0..n} Stirling1(n,j) * Stirling1(j,k). - Seiichi Manyama, Feb 13 2022

A341587 E.g.f.: log(1 + log(1 - x))^2 / 2.

Original entry on oeis.org

1, 6, 40, 315, 2908, 30989, 375611, 5112570, 77305024, 1286640410, 23387713930, 461187042992, 9808283703684, 223833267479764, 5456669750439788, 141540592345674800, 3892707724320135616, 113153294901088030320, 3466501398608272647984, 111636571036702743967104, 3770483138507706753943584
Offset: 2

Views

Author

Ilya Gutkovskiy, Feb 15 2021

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 22; CoefficientList[Series[Log[1 + Log[1 - x]]^2/2, {x, 0, nmax}], x] Range[0, nmax]! // Drop[#, 2] &
    Table[Sum[Abs[StirlingS1[n, k] StirlingS1[k, 2]], {k, 2, n}], {n, 2, 22}]

Formula

a(n) = Sum_{k=2..n} |Stirling1(n, k) * Stirling1(k, 2)|.
a(n) = Sum_{k=2..n} |Stirling1(n, k)| * (k-1)! * H(k-1), where H(k) is the k-th harmonic number.
a(n) = Sum_{k=1..n-1} binomial(n-1, k) * A003713(k) * A003713(n-k).
a(n) = A052822(n) / 2.
a(n) ~ sqrt(2*Pi) * log(n) * n^(n - 1/2) / (exp(1) - 1)^n * (1 + (gamma - log(exp(1) - 1))/log(n)), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, Feb 15 2021

A325872 T(n, k) = [x^k] Sum_{k=0..n} Stirling1(n, k)*FallingFactorial(x, k), triangle read by rows, for n >= 0 and 0 <= k <= n.

Original entry on oeis.org

1, 0, 1, 0, -2, 1, 0, 7, -6, 1, 0, -35, 40, -12, 1, 0, 228, -315, 130, -20, 1, 0, -1834, 2908, -1485, 320, -30, 1, 0, 17582, -30989, 18508, -5005, 665, -42, 1, 0, -195866, 375611, -253400, 81088, -13650, 1232, -56, 1, 0, 2487832, -5112570, 3805723, -1389612, 279048, -32130, 2100, -72, 1
Offset: 0

Views

Author

Peter Luschny, Jun 27 2019

Keywords

Examples

			Triangle starts:
[0] [1]
[1] [0,       1]
[2] [0,      -2,        1]
[3] [0,       7,       -6,       1]
[4] [0,     -35,       40,     -12,        1]
[5] [0,     228,     -315,     130,      -20,      1]
[6] [0,   -1834,     2908,   -1485,      320,    -30,      1]
[7] [0,   17582,   -30989,   18508,    -5005,    665,    -42,    1]
[8] [0, -195866,   375611, -253400,    81088, -13650,   1232,  -56,   1]
[9] [0, 2487832, -5112570, 3805723, -1389612, 279048, -32130, 2100, -72, 1]
		

Crossrefs

Columns k=0..3 give A000007, (-1)^(n+1) * A003713(n), (-1)^n * A341587(n), (-1)^(n+1) * A341588(n).
Cf. A039814 (variant), A129062, A325873.

Programs

  • Mathematica
    p[n_] := Sum[StirlingS1[n, k] FactorialPower[x, k] , {k, 0, n}];
    Table[CoefficientList[FunctionExpand[p[n]], x], {n, 0, 9}] // Flatten
  • PARI
    T(n, k) = sum(j=k, n, stirling(n, j, 1)*stirling(j, k, 1)); \\ Seiichi Manyama, Apr 18 2025
  • Sage
    def a_row(n):
        s = sum((-1)^(n-k)*stirling_number1(n,k)*falling_factorial(x,k) for k in (0..n))
        return expand(s).list()
    [a_row(n) for n in (0..9)]
    

Formula

From Seiichi Manyama, Apr 18 2025: (Start)
T(n,k) = Sum_{j=k..n} Stirling1(n,j) * Stirling1(j,k).
E.g.f. of column k (with leading zeros): f(x)^k / k! with f(x) = log(1 + log(1 + x)). (End)

A341589 a(n) = Sum_{k=n..2*n} |Stirling1(2*n, k) * Stirling1(k, n)|.

Original entry on oeis.org

1, 2, 40, 1485, 81088, 5856900, 526685269, 56704848200, 7112345477952, 1018548226480356, 163987811350464660, 29321558852248050388, 5764958268855541178967, 1236150756215397667568170, 287086392921014590422630300, 71789589754855255636302048525, 19231403740347427723119910379040
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 15 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[Abs[StirlingS1[2 n, k] StirlingS1[k, n]], {k, n, 2 n}], {n, 0, 16}]
    Table[((2 n)!/n!) SeriesCoefficient[(-Log[1 + Log[1 - x]])^n, {x, 0, 2 n}], {n, 0, 16}]
  • PARI
    a(n) = sum(k=n, 2*n, abs(stirling(2*n, k, 1)*stirling(k, n, 1))); \\ Michel Marcus, Feb 16 2021

Formula

a(n) = ((2*n)!/n!) * [x^(2*n)] (-log(1 + log(1 - x)))^n.
From Vaclav Kotesovec, Feb 15 2021: (Start)
a(n) ~ c * d^n * (n-1)!, where
d = -16*p*q^2 * log(-2*q/(1+r))^(1+r) / ((1 + 2*q + r)^2 * (1 + 1/(p*(1+r)))^r) = 17.84101281316291323354184111891200669611476053165484517795417711039479218...
p = LambertW(-1, -1/(exp(1/(1+r))*(1+r)))
q = LambertW(-1, -(1+r)/exp((1+r)/2)/2)
r = 0.5094050884976689299791685259225203723646676600942448390861428232759777841...
is the root of the equation (1+p)*(1+r)^2 * (1 + 2*q + r) * log(-p*(1+r)) + 2*log(-(1+r)/(2*q)) * ((1+q)*(1 + p + p*r) - (1+r) * log(-p*(1+r)) * (p - q + r + p*r + (1+p) * (1+q) * (1+r) * (log(1 + 1/(p*(1+r))) - log(-log(-(1+r)/(2*q)))))) = 0
and c = 0.1417076025518808268972093339771762801784527709... (End)

A383172 Expansion of e.g.f. -log(1 + log(1 - 2*x)/2)^3 / 6.

Original entry on oeis.org

0, 0, 0, 1, 18, 295, 5115, 96838, 2012724, 45825148, 1137703140, 30643915984, 891001127016, 27835772321344, 930387252759328, 33141746095999552, 1253756533365348992, 50210676392866266880, 2122613151692627299584, 94470824166941637093376
Offset: 0

Views

Author

Seiichi Manyama, Apr 18 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=3, n, 2^(n-k)*abs(stirling(n, k, 1)*stirling(k, 3, 1)));

Formula

a(n) = Sum_{k=3..n} 2^(n-k) * |Stirling1(n,k) * Stirling1(k,3)|.
Showing 1-5 of 5 results.