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 1-9 of 9 results.

A376872 a(n) = n! * 2^(-n) * binomial(3*n - 1, 2*n) * binomial(2*n, n). Central terms of the Bessel triangle A132062.

Original entry on oeis.org

1, 1, 15, 420, 17325, 945945, 64324260, 5237832600, 496939367925, 53835098191875, 6557114959770375, 886998823648938000, 131941075017779527500, 21404902093269001807500, 3761147082102981746175000, 711609027933884146376310000, 144234254849349142918648333125
Offset: 0

Views

Author

Peter Luschny, Oct 26 2024

Keywords

Crossrefs

Programs

  • Maple
    a := n -> ifelse(n = 0, 1, (3*n)! / (3* 2^n * n!^2)): seq(a(n), n = 0..16);
    # Alternative:
    gf := 1 + x*hypergeom([4/3, 5/3], [2], (27*x)/2): ser := series(gf, x, 18):
    seq(ifelse(n=0, 1, (n-1)!)*coeff(ser, x, n), n = 0..16);
    # Or:
    a := proc(n) option remember; if n < 2 then return 1 fi;
    a(n - 1)*(27*n^3 - 54*n^2 + 33*n - 6)/(2*n^2 - 2*n) end:
  • Mathematica
    Table[n!2^(-n)Binomial[3n-1,2n]Binomial[2n,n],{n,0,16}] (* James C. McMahon, Oct 27 2024 *)

Formula

a(n) = binomial(2*n-2*k, n-k)*binomial(2*n-k-1, k-1)*(n-k)!/2^(n-k) = A132062(2*n, n).
a(n) = (3*n)! / (3 * 2^n * n!^2) for n >= 1, that is A245066(n) / 3 for n >= 1.
a(n) = (n-1)! * [x^n] (1 + x*hypergeom([4/3, 5/3], [2], (27*x)/2)) for n >= 1.
a(n) = a(n - 1)*(27*n^3 - 54*n^2 + 33*n - 6)/(2*n^2 - 2*n).

A039683 Signed double Pochhammer triangle: expansion of x(x-2)(x-4)..(x-2n+2).

Original entry on oeis.org

1, -2, 1, 8, -6, 1, -48, 44, -12, 1, 384, -400, 140, -20, 1, -3840, 4384, -1800, 340, -30, 1, 46080, -56448, 25984, -5880, 700, -42, 1, -645120, 836352, -420224, 108304, -15680, 1288, -56, 1, 10321920, -14026752, 7559936, -2153088, 359184, -36288, 2184, -72, 1
Offset: 1

Views

Author

Keywords

Comments

T(n,m) = R_n^m(a=0,b=2) in the notation of the given reference.
Exponential Riordan array [1/(1+2x),log(1+2x)/2]. The unsigned triangle is [1/(1-2x),log(1/sqrt(1-2x))]. - Paul Barry_, Apr 29 2009
The n-th row is related to the expansion of z^(-2n)*(z^3 d/dz)^n in polynomials of the Euler operator D=(z d/dz). E.g., z^(-6)(z^3 d/dz)^3 = D^3 + 6 D^2 + 8 D. See Copeland link for relations to Bell / Exponential / Touchard polynomial operators. - Tom Copeland, Nov 14 2013
A refinement of this array is given by A231846. - Tom Copeland, Nov 15 2013
Also the Bell transform of the double factorial of even numbers A000165 except that the values are unsigned and in addition a first column (1,0,0 ...) is added on the left side of the triangle. For the Bell transform of the double factorial of odd numbers A001147 see A132062. For the definition of the Bell transform see A264428. - Peter Luschny, Dec 20 2015
The signed triangle is also the inverse Bell transform of A000079 (see Luschny link). - John Keith, Nov 24 2020

Examples

			Triangle starts:
  {1},
  {2,1},
  {8,6,1},
  {48,44,12,1},
  ...
From _Paul Barry_, Apr 29 2009: (Start)
The unsigned triangle [1/(1-2x),log(1/sqrt(1-2x))] has production matrix:
  2, 1,
  4, 4, 1,
  8, 12, 6, 1,
  16, 32, 24, 8, 1,
  32, 80, 80, 40, 10, 1,
  64, 192, 240, 160, 60, 12, 1
which is A007318^{2} beheaded. (End)
		

Crossrefs

First column (unsigned triangle) is (2(n-1))!! = 1, 2, 8, 48, 384...= A000165(n-1) and the row sums (unsigned) are (2n-1)!! = 1, 3, 15, 105, 945... = A001147(n-1).
Cf. A038207.

Programs

  • Mathematica
    Table[ Rest@ CoefficientList[ Product[ z-k, {k, 0, 2p-2, 2} ], z ], {p, 6} ]
  • Sage
    # uses[bell_transform from A264428]
    # Unsigned values and an additional first column (1,0,0,...).
    def A039683_unsigned_row(n):
        a = sloane.A000165
        dblfact = a.list(n)
        return bell_transform(n, dblfact)
    [A039683_unsigned_row(n) for n in (0..9)] # Peter Luschny, Dec 20 2015

Formula

T(n, m) = T(n-1, m-1) - 2*(n-1)*T(n-1, m), n >= m >= 1; T(n, m) := 0, n
E.g.f. for m-th column of signed triangle: (((log(1+2*x))/2)^m)/m!.
E.g.f.: (1+2*x)^(y/2). O.g.f. for n-th row of signed triangle: Sum_{m=0..n} Stirling1(n, m)*2^(n-m)*x^m. - Vladeta Jovovic, Feb 11 2003
T(n, m) = S1(n, m)*2^(n-m), with S1(n, m) := A008275(n, m) (signed Stirling1 triangle).
The production matrix below is A038207 with the first row removed. With the initial index n = 0, the associated differential raising operator is R = e^(2D)*x = (2+x)*e^(2D) with D = d/dx, i.e., R p_n(x) = p_(n+1)(x) where p_n(x) is the n-th unsigned row polynomial and p_0(x) = 1, so p_(n+1)(x) = (2+x) * p_n(2+x). - Tom Copeland, Oct 11 2016

Extensions

Additional comments from Wolfdieter Lang
Title revised by Tom Copeland, Dec 21 2013

A004747 Triangle read by rows: the Bell transform of the triple factorial numbers A008544 without column 0.

Original entry on oeis.org

1, 2, 1, 10, 6, 1, 80, 52, 12, 1, 880, 600, 160, 20, 1, 12320, 8680, 2520, 380, 30, 1, 209440, 151200, 46480, 7840, 770, 42, 1, 4188800, 3082240, 987840, 179760, 20160, 1400, 56, 1, 96342400, 71998080, 23826880, 4583040, 562800, 45360, 2352, 72, 1
Offset: 1

Keywords

Comments

Previous name was: Triangle of numbers related to triangle A048966; generalization of Stirling numbers of second kind A008277, Bessel triangle A001497.
T(n,m) = S2p(-2; n,m), a member of a sequence of triangles including S2p(-1; n,m) = A001497(n-1,m-1) (Bessel triangle) and ((-1)^(n-m))*S2p(1; n,m) = A008277(n, m) (Stirling 2nd kind). T(n,1)= A008544(n-1).
T(n,m), n>=m>=1, enumerates unordered n-vertex m-forests composed of m plane (aka ordered) increasing (rooted) trees where vertices of out-degree r>=0 come in r+1 different types (like an (r+1)-ary vertex). Proof from the e.g.f. of the first column Y(z) = 1 - (1-3*x)^(1/3) and the F. Bergeron et al. eq. (8) Y'(z)= phi(Y(z)), Y(0) = 0, with out-degree o.g.f. phi(w)=1/(1-w)^2. - Wolfdieter Lang, Oct 12 2007
Also the Bell transform of the triple factorial numbers A008544 which adds a first column (1,0,0 ...) on the left side of the triangle. For the definition of the Bell transform see A264428. See A051141 for the triple factorial numbers A032031 and A203412 for the triple factorial numbers A007559 as well as A039683 and A132062 for the case of double factorial numbers. - Peter Luschny, Dec 21 2015

Examples

			Triangle begins:
       1;
       2,      1;
      10,      6,     1;
      80,     52,    12,    1;
     880,    600,   160,   20,   1;
   12320,   8680,  2520,  380,  30,  1;
  209440, 151200, 46480, 7840, 770, 42, 1;
Tree combinatorics for T(3,2)=6: Consider first the unordered forest of m=2 plane trees with n=3 vertices, namely one vertex with out-degree r=0 (root) and two different trees with two vertices (one root with out-degree r=1 and a leaf with r=0). The 6 increasing labelings come then from the forest with rooted (x) trees x, o-x (1,(3,2)), (2,(3,1)) and (3,(2,1)) and similarly from the second forest x, x-o (1,(2,3)), (2,(1,3)) and (3,(1,2)).
		

Crossrefs

Cf. A015735 (row sums).
Triangles with the recurrence T(n,k) = (m*(n-1)-k)*T(n-1,k) + T(n-1,k-1): A010054 (m=1), A001497 (m=2), this sequence (m=3), A000369 (m=4), A011801 (m=5), A013988 (m=6).

Programs

  • Magma
    function T(n,k) // T = A004747
      if k eq 0 then return 0;
      elif k eq n then return 1;
      else return (3*(n-1)-k)*T(n-1,k) + T(n-1,k-1);
      end if;
    end function;
    [T(n,k): k in [1..n], n in [1..12]]; // G. C. Greubel, Oct 03 2023
  • Maple
    T := (n, m) -> 3^n/m!*(1/3*m*GAMMA(n-1/3)*hypergeom([1-1/3*m, 2/3-1/3*m, 1/3-1/3*m], [2/3, 4/3-n], 1)/GAMMA(2/3)-1/6*m*(m-1)*GAMMA(n-2/3)*hypergeom( [1-1/3*m, 2/3-1/3*m, 4/3-1/3*m], [4/3, 5/3-n], 1)/Pi*3^(1/2)*GAMMA(2/3)):
    for n from 1 to 6 do seq(simplify(T(n,k)),k=1..n) od;
    # Karol A. Penson, Feb 06 2004
    # The function BellMatrix is defined in A264428.
    # Adds (1,0,0,0, ..) as column 0.
    BellMatrix(n -> mul(3*k+2, k=(0..n-1)), 9); # Peter Luschny, Jan 29 2016
  • Mathematica
    (* First program *)
    T[1,1]= 1; T[, 0]= 0; T[0, ]= 0; T[n_, m_]:= (3*(n-1)-m)*T[n-1, m]+T[n-1, m-1];
    Flatten[Table[T[n, m], {n,12}, {m,n}] ][[1 ;; 45]] (* Jean-François Alcover, Jun 16 2011, after recurrence *)
    (* Second program *)
    f[n_, m_]:= m/n Sum[Binomial[k, n-m-k] 3^k (-1)^(n-m-k) Binomial[n+k-1, n-1], {k, 0, n-m}]; Table[n! f[n, m]/(m! 3^(n-m)), {n,12}, {m,n}]//Flatten (* Michael De Vlieger, Dec 23 2015 *)
    (* Third program *)
    rows = 12;
    T[n_, m_]:= BellY[n, m, Table[Product[3k+2, {k, 0, j-1}], {j, 0, rows}]];
    Table[T[n, m], {n,rows}, {m,n}]//Flatten (* Jean-François Alcover, Jun 22 2018 *)
  • Sage
    # uses [bell_transform from A264428]
    triplefactorial = lambda n: prod(3*k+2 for k in (0..n-1))
    def A004747_row(n):
        trifact = [triplefactorial(k) for k in (0..n)]
        return bell_transform(n, trifact)
    [A004747_row(n) for n in (0..10)] # Peter Luschny, Dec 21 2015
    

Formula

T(n, m) = n!*A048966(n, m)/(m!*3^(n-m));
T(n+1, m) = (3*n-m)*T(n, m)+ T(n, m-1), for n >= m >= 1, with T(n, m) = 0, for n
E.g.f. of m-th column: ( 1 - (1-3*x)^(1/3) )^m/m!.
Sum_{k=1..n} T(n, k) = A015735(n).
For a formula expressed as special values of hypergeometric functions 3F2 see the Maple program below. - Karol A. Penson, Feb 06 2004
T(n,1) = A008544(n-1). - Peter Luschny, Dec 23 2015

Extensions

New name from Peter Luschny, Dec 21 2015

A051141 Triangle read by rows: a(n, m) = S1(n, m)*3^(n-m), where S1 are the signed Stirling numbers of first kind A008275 (n >= 1, 1 <= m <= n).

Original entry on oeis.org

1, -3, 1, 18, -9, 1, -162, 99, -18, 1, 1944, -1350, 315, -30, 1, -29160, 22194, -6075, 765, -45, 1, 524880, -428652, 131544, -19845, 1575, -63, 1, -11022480, 9526572, -3191076, 548289, -52920, 2898, -84, 1, 264539520, -239660208
Offset: 1

Keywords

Comments

Previous name was: Generalized Stirling number triangle of first kind.
a(n,m) = R_n^m(a=0,b=3) in the notation of the given reference.
a(n,m) is a Jabotinsky matrix, i.e., the monic row polynomials E(n,x) := Sum_{m=1..n} a(n,m)*x^m = Product_{j=0..n-1} (x - 3*j), n >= 1 and E(0,x) := 1 are exponential convolution polynomials (see A039692 for the definition and a Knuth reference).
This is the signed Stirling1 triangle with diagonals d>=0 (main diagonal d=0) scaled with 3^d.
Exponential Riordan array [1/(1 + 3*x), log(1 + 3*x)/3]. The unsigned triangle is [1/(1 - 3*x), log(1/(1 - 3*x)^(1/3))]. - Paul Barry, Apr 29 2009
Also the Bell transform of the triple factorial numbers A032031 which adds a first column (1, 0, 0 ...) on the left side of the triangle and computes the unsigned values. For the definition of the Bell transform, see A264428. See A004747 for the triple factorial numbers A008544 and A203412 for the triple factorial numbers A007559 as well as A039683 and A132062 for the case of double factorial numbers. - Peter Luschny, Dec 21 2015

Examples

			Triangle starts:
       1;
      -3,       1;
      18,      -9,      1;
    -162,      99,    -18,      1;
    1944,   -1350,    315,    -30,    1;
  -29160,   22194,  -6075,    765,  -45,   1;
  524880, -428652, 131544, -19845, 1575, -63, 1;
---
Row polynomial E(3,x) = 18*x-9*x^2+x^3.
From _Paul Barry_, Apr 29 2009: (Start)
The unsigned array [1/(1 - 3*x), log(1/(1 - 3*x)^(1/3))] has production matrix
    3,    1;
    9,    6,    1;
   27,   27,    9,   1;
   81,  108,   54,  12,   1;
  243,  405,  270,  90,  15,  1;
  729, 1458, 1215, 540, 135, 18, 1;
  ...
which is A007318^{3} beheaded (by viewing A007318 as a lower triangular matrix). See the comment above. (End)
		

Crossrefs

First (m=1) column sequence is: A032031(n-1).
Row sums (signed triangle): A008544(n-1)*(-1)^(n-1).
Row sums (unsigned triangle): A007559(n).
Cf. A008275 (Stirling1 triangle, b=1), A039683 (b=2), A051142 (b=4).

Programs

Formula

a(n, m) = a(n-1, m-1) - 3*(n-1)*a(n-1, m) for n >= m >= 1; a(n, m) = 0 for n < m; a(n, 0) = 0 for n >= 1; a(0, 0) = 1.
E.g.f. for the m-th column of the signed triangle: (log(1 + 3*x)/3)^m/m!.
|a(n,1)| = A032031(n-1). - Peter Luschny, Dec 23 2015

Extensions

Name clarified using a formula of the author by Peter Luschny, Dec 23 2015

A203412 Triangle read by rows, a(n,k), n>=k>=1, which represent the s=3, h=1 case of a two-parameter generalization of Stirling numbers arising in conjunction with normal ordering.

Original entry on oeis.org

1, 1, 1, 4, 3, 1, 28, 19, 6, 1, 280, 180, 55, 10, 1, 3640, 2260, 675, 125, 15, 1, 58240, 35280, 10360, 1925, 245, 21, 1, 1106560, 658000, 190680, 35385, 4620, 434, 28, 1, 24344320, 14266560, 4090240, 756840, 100065, 9828, 714, 36, 1
Offset: 1

Author

Mark Shattuck, Jan 01 2012

Keywords

Comments

Also the Bell transform of the triple factorial numbers A007559 which adds a first column (1,0,0 ...) on the left side of the triangle. For the definition of the Bell transform see A264428. See A051141 for the triple factorial numbers A032031 and A004747 for the triple factorial numbers A008544 as well as A039683 and A132062 for the case of double factorial numbers. - Peter Luschny, Dec 23 2015

Examples

			Triangle starts:
[    1]
[    1,     1]
[    4,     3,     1]
[   28,    19,     6,    1]
[  280,   180,    55,   10,   1]
[ 3640,  2260,   675,  125,  15,  1]
[58240, 35280, 10360, 1925, 245, 21, 1]
		

Programs

  • Maple
    A203412 := (n,k) -> (n!*3^n)/(k!*2^k)*add((-1)^j*binomial(k,j)*binomial(n-2*j/3-1, n), j=0..k): seq(seq(A203412(n,k),k=1..n),n=1..9); # Peter Luschny, Dec 21 2015
  • Mathematica
    Table[(n! 3^n)/(k! 2^k) Sum[ (-1)^j Binomial[k, j] Binomial[n - 2 j/3 - 1, n], {j, 0, k}], {n, 9}, {k, n}] // Flatten (* Michael De Vlieger, Dec 23 2015 *)
  • Sage
    # uses[bell_transform from A264428]
    triplefactorial = lambda n: prod(3*k + 1 for k in (0..n-1))
    def A203412_row(n):
        trifact = [triplefactorial(k) for k in (0..n)]
        return bell_transform(n, trifact)
    [A203412_row(n) for n in (0..8)] # Peter Luschny, Dec 21 2015

Formula

(1) Is given by the recurrence relation
a(n+1,k) = a(n,k-1)+(3*n-2*k)*a(n,k) if n>=0 and k>=1, along with the initial values a(n,0) = delta_{n,0} and a(0,k) = delta_{0,k} for all n,k>=0.
(2) Is given explicitly by
a(n,k) = (n!*3^n)/(k!*2^k)*Sum{j=0..k} (-1)^j*C(k,j)*C(n-2*j/3-1,n) for all n>=k>=1.
a(n,1) = A007559(n-1). - Peter Luschny, Dec 21 2015

A265606 Triangle read by rows: The Bell transform of the quartic factorial numbers (A007696).

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 5, 3, 1, 0, 45, 23, 6, 1, 0, 585, 275, 65, 10, 1, 0, 9945, 4435, 990, 145, 15, 1, 0, 208845, 89775, 19285, 2730, 280, 21, 1, 0, 5221125, 2183895, 456190, 62965, 6370, 490, 28, 1, 0, 151412625, 62002395, 12676265, 1715490, 171255, 13230, 798, 36, 1
Offset: 0

Author

Peter Luschny, Dec 30 2015

Keywords

Examples

			[1],
[0, 1],
[0, 1, 1],
[0, 5, 3, 1],
[0, 45, 23, 6, 1],
[0, 585, 275, 65, 10, 1],
[0, 9945, 4435, 990, 145, 15, 1],
[0, 208845, 89775, 19285, 2730, 280, 21, 1],
		

Crossrefs

Bell transforms of other multifactorials are: A000369, A004747, A039683, A051141, A051142, A119274, A132062, A132393, A203412.

Programs

  • Mathematica
    (* The function BellMatrix is defined in A264428. *)
    rows = 10;
    M = BellMatrix[Pochhammer[1/4, #] 4^# &, rows];
    Table[M[[n, k]], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jul 23 2019 *)
  • Sage
    # uses[bell_transform from A264428]
    def A265606_row(n):
        multifact_4_1 = lambda n: prod(4*k + 1 for k in (0..n-1))
        mfact = [multifact_4_1(k) for k in (0..n)]
        return bell_transform(n, mfact)
    [A265606_row(n) for n in (0..7)]

A122850 Exponential Riordan array (1, sqrt(1+2x)-1).

Original entry on oeis.org

1, 0, 1, 0, -1, 1, 0, 3, -3, 1, 0, -15, 15, -6, 1, 0, 105, -105, 45, -10, 1, 0, -945, 945, -420, 105, -15, 1, 0, 10395, -10395, 4725, -1260, 210, -21, 1, 0, -135135, 135135, -62370, 17325, -3150, 378, -28, 1, 0, 2027025, -2027025, 945945, -270270, 51975, -6930, 630, -36, 1
Offset: 0

Author

Paul Barry, Sep 14 2006

Keywords

Comments

Inverse of number triangle A122848. Entries are Bessel polynomial coefficients. Row sums are A000806.
Also the inverse Bell transform of the sequence "g(n) = 1 if n<2 else 0". For the definition of the Bell transform see A264428. - Peter Luschny, Jan 19 2016

Examples

			Triangle begins
  1
  0 1
  0 -1 1
  0 3 -3 1
  0 -15 15 -6 1
  0 105 -105 45 -10 1
  0 -945 945 -420 105 -15 1
  0 10395 -10395 4725 -1260 210 -21 1
  0 -135135 135135 -62370 17325 -3150 378 -28 1
  0 2027025 -2027025 945945 -270270 51975 -6930 630 -36 1
  0 -34459425 34459425 -16216200 4729725 -945945 135135 -13860 990 -45 1
  ...
		

Programs

  • Maple
    # The function BellMatrix is defined in A264428.
    BellMatrix(n -> (-1)^n*doublefactorial(2*n-1), 9); # Peter Luschny, Jan 27 2016
  • Mathematica
    BellMatrix[f_Function, len_] := With[{t = Array[f, len, 0]}, Table[BellY[n, k, t], {n, 0, len - 1}, {k, 0, len - 1}]];
    rows = 12;
    M = BellMatrix[Function[n, (-1)^n (2n-1)!!], rows];
    Table[M[[n, k]], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 26 2018, after Peter Luschny *)
  • Sage
    # uses[bell_matrix from A264428]
    bell_matrix(lambda n: 1 if n<2 else 0, 12).inverse() # Peter Luschny, Jan 19 2016

Formula

T(n,k) = (-1)^(n-k)*A132062(n,k). - Philippe Deléham, Nov 06 2011
Triangle equals the matrix product A039757*A008277. Dobinski-type formula for the row polynomials: R(n,x) = x*exp(-x)*Sum_{k = 0..inf} (k-1)*(k-3)*(k-5)*...*(k-(2*n-3))*x^k/k! for n >= 1. Cf. A001497. - Peter Bala, Jun 23 2014
From Peter Bala, Jan 09 2018: (Start)
Alternative Dobinski-type formula for the row polynomials: R(n,x) = exp(-x)*Sum_{k = 0..inf} k*(k-2)*(k-4)*...*(k-(2*n-2))*x^k/k!.
Equivalently, R(n,x) = x o (x-2) o (x-4) o...o (x-(2*n-2)), where o denotes the white diamond product of polynomials. See the Bala link for the definition and details.
The white diamond products (x-1) o (x-3) o...o (x-(2*n-3)) give the row polynomials of the array with a factor of x removed.
If d is the first derivative operator f -> d/dx(f(x)) and D is the operator f(x) -> 1/x*d/dx(f(x)) then x^(2*n)*D^n = R(n,x*d), with the understanding that (x*d)^k is to interpreted as the operator f(x) -> x^k*d^k(f(x))/dx^k. (End)
Sum_{k=0..n} (-1)^(n+k) * T(n,k) = A144301(n). - Alois P. Heinz, Aug 31 2022

Extensions

More terms from Alois P. Heinz, Aug 31 2022

A305402 A number triangle T(n,k) read by rows for 0<=k<=n, related to the Taylor expansion of f(u, p) = (1/2)*(1+1/(sqrt(1-u^2)))*exp(p*sqrt(1-u^2)).

Original entry on oeis.org

1, 1, -2, 3, -4, 2, 15, -18, 9, -2, 105, -120, 60, -16, 2, 945, -1050, 525, -150, 25, -2, 10395, -11340, 5670, -1680, 315, -36, 2, 135135, -145530, 72765, -22050, 4410, -588, 49, -2, 2027025, -2162160, 1081080, -332640, 69300, -10080, 1008, -64, 2
Offset: 0

Author

Johannes W. Meijer, May 31 2018

Keywords

Comments

The function f(u, p) = (1/2)*(1+1/(sqrt(1-u^2))) * exp(p*sqrt(1-u^2)) was found while studying the Fresnel-Kirchhoff and the Rayleigh-Sommerfeld theories of diffraction, see the Meijer link.
The Taylor expansion of f(u, p) leads to the number triangle T(n, k), see the example section.
Normalization of the triangle terms, dividing the T(n, k) by T(n-k, 0), leads to A084534.
The row sums equal A003436, n >= 2, respectively A231622, n >= 1.

Examples

			The first few terms of the Taylor expansion of f(u; p) are:
f(u, p) = exp(p) * (1 + (1-2*p) * u^2/4 + (3-4*p+2*p^2) * u^4/16 + (15-18*p+9*p^2-2*p^3) * u^6/96 + (105-120*p+60*p^2-16*p^3+2*p^4) * u^8/768 + ... )
The first few rows of the T(n, k) triangle are:
n=0:     1
n=1:     1,     -2
n=2:     3,     -4,    2
n=3:    15,    -18,    9,    -2
n=4:   105,   -120,   60,   -16,   2
n=5:   945,  -1050,  525,  -150,  25,  -2
n=6: 10395, -11340, 5670, -1680, 315, -36, 2
		

References

  • J. W. Goodman, Introduction to Fourier Optics, 1996.
  • A. Papoulis, Systems and Transforms with Applications in Optics, 1968.

Crossrefs

Cf. Related to the left hand columns: A001147, A001193, A261065.
Cf. Related to the right hand columns: A280560, A162395, A006011, A040977, A053347, A054334, A266561.

Programs

  • Magma
    [[n le 0 select 1 else (-1)^k*2^(k-n+1)*Factorial(2*n-k-1)*Binomial(n, k)/Factorial(n-1): k in [0..n]]: n in [1..10]]; // G. C. Greubel, Nov 08 2018
  • Maple
    T := proc(n, k): if n=0 then 1 else (-1)^k*2^(k-n+1)*n*(2*n-k-1)!/(k!*(n-k)!) fi: end: seq(seq(T(n, k), k=0..n), n=0..8);
  • Mathematica
    Table[If[n==0 && k==0,1, (-1)^k*2^(k-n+1)*n*(2*n-k-1)!/(k!*(n-k)!)], {n, 0, 10}, {k,0,n}]//Flatten (* G. C. Greubel, Nov 08 2018 *)
  • PARI
    T(n,k) = {if(n==0, 1, (-1)^k*2^(k-n+1)*n*(2*n-k-1)!/(k!*(n-k)!))}
    for(n=0, 10, for(k=0, n, print1(T(n, k), ", ")); print); \\ Andrew Howroyd, Nov 08 2018
    

Formula

T(n, k) = (-1)^k*2^(k-n+1)*n*(2*n-k-1)!/(k!*(n-k)!), n > 0 and 0 <= k <= n, T(0, 0) = 1.
T(n, k) = (-1)^k*A001147(n-k)*A084534(n, k), n >= 0 and 0 <= k <= n.
T(n, k) = 2^(2*(k-n)+1)*A001147(n-k)*A127674(n, n-k), n > 0 and 0 <= k <= n, T(0, 0) = 1.
T(n, k) = (-1)^k*(A001497(n, k) + A132062(n, k)), n >= 1, T(0,0) = 1.

A369746 Expansion of e.g.f. exp( 3 * (1-sqrt(1-2*x)) ).

Original entry on oeis.org

1, 3, 12, 63, 423, 3528, 35559, 422901, 5817744, 91072269, 1600588269, 31230827532, 670252672593, 15696888917427, 398454496989012, 10899543418960167, 319672849622745951, 10007954229075765984, 333139545206104991031, 11749955670275356579941
Offset: 0

Author

Seiichi Manyama, Jan 30 2024

Keywords

Crossrefs

Programs

  • Maple
    # The row polynomials of A132062 evaluated at x = 3.
    T := proc(n, k) option remember; if k = 0 then 0^n elif n < k then 0
    else (2*(n - 1) - k)*T(n - 1, k) + T(n - 1, k - 1) fi end:
    seq(add(T(n, k)*3^k, k = 0..n), n = 0..19);  # Peter Luschny, Apr 25 2024
  • Mathematica
    With[{nn=20},CoefficientList[Series[Exp[3(1-Sqrt[1-2x])],{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Apr 14 2025 *)
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(3*(1-sqrt(1-2*x)))))

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} 3^(n-k) * (n-1+k)! / (2^k * k! * (n-1-k)!).
a(n) = (2*n-3)*a(n-1) + 9*a(n-2).
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