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.

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A269946 Triangle read by rows, Lah numbers of order 3, T(n,n) = 1, T(n,k) = 0 if k<0 or k>n, otherwise T(n,k) = T(n-1,k-1)+((n-1)^3+k^3)*T(n-1, k), for n>=0 and 0<=k<=n.

Original entry on oeis.org

1, 0, 1, 0, 2, 1, 0, 18, 18, 1, 0, 504, 648, 72, 1, 0, 32760, 47160, 7200, 200, 1, 0, 4127760, 6305040, 1141560, 45000, 450, 1, 0, 895723920, 1416456720, 283704120, 13741560, 198450, 882, 1, 0, 308129028480, 498072032640, 106386981120, 5876519040, 106616160, 691488, 1568, 1
Offset: 0

Views

Author

Peter Luschny, Mar 22 2016

Keywords

Examples

			Triangle starts:
[1]
[0, 1]
[0, 2,       1]
[0, 18,      18,      1]
[0, 504,     648,     72,      1]
[0, 32760,   47160,   7200,    200,   1]
[0, 4127760, 6305040, 1141560, 45000, 450, 1]
		

Crossrefs

Cf. A038207 (order 0), A111596 (order 1), A268434 (order 2).

Programs

  • Maple
    T := proc(n, k) option remember;
        `if`(n=k, 1,
        `if`(k<0 or k>n, 0,
         T(n-1, k-1) + ((n-1)^3+k^3) * T(n-1, k) )) end:
    for n from 0 to 6 do seq(T(n,k), k=0..n) od;
  • Mathematica
    T[n_, n_] = 1; T[, 0] = 0; T[n, k_] /; 0 < k < n := T[n, k] = T[n-1, k-1] + ((n-1)^3 + k^3)*T[n-1, k]; T[, ] = 0;
    Table[T[n, k], {n, 0, 8}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jun 20 2017 *)

Formula

T(n,k) = Sum_{j=k..n} A269947(n,j)*A269948(j,k).
T(n,1) = Product_{k=1..n} (k-1)^3+1 for n>=1 (cf. A255433).
T(n,n-1) = (n-1)^2*n^2/2 for n>=1 (cf. A163102).

A344051 a(n) = Sum_{k=0..n} binomial(n, k)*|Lah(n, k)|. Binomial convolution of the unsigned Lah numbers A271703.

Original entry on oeis.org

1, 1, 5, 37, 361, 4301, 60001, 954325, 16984577, 333572041, 7151967181, 165971975621, 4139744524345, 110333560295557, 3126749660583641, 93819198847833061, 2969676820062708481, 98843743790129998865, 3449675368718647501717, 125921086600579132143781, 4796519722094585691925961
Offset: 0

Views

Author

Peter Luschny, May 10 2021

Keywords

Crossrefs

Programs

  • Maple
    aList := proc(len) local lah;
    lah := (n, k) -> `if`(n = k, 1, binomial(n-1, k-1)*n!/k!):
    seq(add(binomial(n, k)*lah(n, k), k = 0..n), n = 0..len-1) end:
    lprint(aList(22));
  • Mathematica
    a[n_] := n n! HypergeometricPFQ[{1 - n, 1 - n}, {2, 2}, 1]; a[0] := 1;
    Table[a[n], {n, 0, 20}]

Formula

a(n) = n * n! * hypergeom([1 - n, 1 - n], [2, 2], 1) for n >= 1.
D-finite with recurrence +16*n*a(n) +6*(-8*n^2+5*n-1)*a(n-1) +(48*n^3-266*n^2+407*n-167)*a(n-2) +(-16*n^4+106*n^3-219*n^2+108*n+93)*a(n-3) +(n-4)*(2*n^3-13*n^2+16*n+25)*a(n-4) -(n-5)*(n-4)^3*a(n-5)=0. - R. J. Mathar, Jul 27 2022
a(n) ~ n^(n - 1/2) / (sqrt(6*Pi) * exp(n - 3*n^(2/3) + n^(1/3) - 1/3)) * (1 + 31/(54*n^(1/3))). - Vaclav Kotesovec, Apr 27 2024
Previous Showing 41-42 of 42 results.