Original entry on oeis.org
1, 4, 21, 142, 1201, 12336, 149989, 2113546, 33926337, 611660476, 12243073621, 269456124774, 6468249055921, 168191402251432, 4709596238204901, 141291441773619106, 4521383010795364609, 153727989225714801396, 5534225015581836134677
Offset: 0
-
CoefficientList[Series[E^x/(1-3*x+2*x^2), {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Oct 02 2013 *)
Original entry on oeis.org
0, 0, 2, 9, 56, 450, 4464, 52920, 731520, 11566800, 206035200, 4083488640, 89137843200, 2124970848000, 54929029478400, 1530259226496000, 45705137084006400, 1456873475016960000, 49362677881380864000
Offset: 0
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
-
spec := [S,{B=Sequence(Z,1 <= card),C=Cycle(B),S=Prod(Z,C)},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
# alternative
A052840 := proc(n)
log((-1+x)/(-1+2*x))*x ;
coeftayl(%,x=0,n)*n! ;
end proc:
seq(A052840(n),n=0..20) ; # R. J. Mathar, Jan 20 2025
-
Flatten[{0, 0, Table[n!*(2^(n-1) - 1)/(n-1), {n, 2, 20}]}] (* Vaclav Kotesovec, Jun 06 2019 *)
Original entry on oeis.org
2, 11, 76, 654, 6816, 83880, 1193760, 19318320, 350622720, 7056927360, 156031142400, 3760042809600, 98093779660800, 2754553785984000, 82841868639129600, 2656672553703168000, 90498598469959680000, 3263440333591646208000
Offset: 0
-
a[n_] := (n - 1)! * (2^n - 1); Table[a[n+2] - a[n+1], {n,0,25}] (* G. C. Greubel, Jan 19 2017 *)
-
for(n=0,25, print1(( (n+1)!*(2^(n+2) -1) - n!*(2^(n+1) -1)), ", ")) \\ G. C. Greubel, Jan 19 2017
Original entry on oeis.org
1, 4, 18, 114, 900, 8845, 103861, 1427122, 22486706, 399906140, 7922936720, 173013117604, 4127746294408, 106806183646594, 2978731438384738, 89065499057526433, 2842061902985159593, 96395720127638538076, 3462922846509648162418
Offset: 0
-
Rest[CoefficientList[Series[Product[1/(1 - x^k)^((k-1)!*(2^k-1)), {k, 1, 20}], {x, 0, 20}], x]] (* Vaclav Kotesovec, Aug 07 2015 *)
A131222
Exponential Riordan array [1, log((1-x)/(1-2x))].
Original entry on oeis.org
1, 0, 1, 0, 3, 1, 0, 14, 9, 1, 0, 90, 83, 18, 1, 0, 744, 870, 275, 30, 1, 0, 7560, 10474, 4275, 685, 45, 1, 0, 91440, 143892, 70924, 14805, 1435, 63, 1, 0, 1285200, 2233356, 1274196, 324289, 41160, 2674, 84, 1
Offset: 0
Number triangle starts:
1,
0, 1;
0, 3, 1;
0, 14, 9, 1;
0, 90, 83, 18, 1;
0, 744, 870, 275, 30, 1;
...
-
RioExp := (d,h,n,k) -> coeftayl(d*h^k, x=0,n)*n!/k!:
A131222 := (n,k) -> RioExp(1,log((1-x)/(1-2*x)),n,k):
seq(print(seq(A131222(n,k),k=0..n)),n=0..5); # Peter Luschny, Apr 15 2015
# The function BellMatrix is defined in A264428.
BellMatrix(n -> `if`(n=0,1,n!*(2^(n+1)-1)), 9); # Peter Luschny, Jan 27 2016
-
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[If[# == 0, 1, #! (2^(#+1) - 1)]&, rows];
Table[M[[n, k]], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 24 2018, after Peter Luschny *)
-
T(n,m):=if n=0 and m=0 then 1 else n!*sum((stirling1(k,m)*2^(n-k)*binomial(n-1,k-1))/k!,k,m,n); /* Vladimir Kruchinin, Sep 27 2012 */
-
def Lah(n, k):
if n == k: return 1
if k<0 or k>n: return 0
return (k*n*gamma(n)^2)/(gamma(k+1)^2*gamma(n-k+1))
matrix(ZZ, 8, Lah) * matrix(ZZ, 8, stirling_number1) # as a square matrix Peter Luschny, Apr 12 2015
# alternatively:
-
# uses[bell_matrix from A264428]
bell_matrix(lambda n: A029767(n+1), 10) # Peter Luschny, Jan 18 2016
A360288
Number T(n,k) of permutations of [n] whose excedance set is the k-th finite subset of positive integers in standard order; triangle T(n,k), n>=0, 0<=k<=ceiling(2^(n-1))-1, read by rows.
Original entry on oeis.org
1, 1, 1, 1, 1, 3, 1, 1, 1, 7, 3, 7, 1, 3, 1, 1, 1, 15, 7, 31, 3, 17, 7, 15, 1, 7, 3, 7, 1, 3, 1, 1, 1, 31, 15, 115, 7, 69, 31, 115, 3, 37, 17, 69, 7, 37, 15, 31, 1, 15, 7, 31, 3, 17, 7, 15, 1, 7, 3, 7, 1, 3, 1, 1, 1, 63, 31, 391, 15, 245, 115, 675, 7, 145, 69
Offset: 0
T(5,4) = 3: there are 3 permutations of [5] with excedance set {3} (the 4th subset in standard order): 12435, 12534, 12543.
Triangle T(n,k) begins:
1;
1;
1, 1;
1, 3, 1, 1;
1, 7, 3, 7, 1, 3, 1, 1;
1, 15, 7, 31, 3, 17, 7, 15, 1, 7, 3, 7, 1, 3, 1, 1;
...
-
b:= proc(s, t) option remember; (m->
`if`(m=0, x^(t/2), add(b(s minus {i}, t+
`if`(i (p-> seq(coeff(p, x, i), i=0..degree(p)))(b({$1..n}, 0)):
seq(T(n), n=0..7);
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b[s_, t_] := b[s, t] = Function [m, If[m == 0, x^(t/2), Sum[b[s ~Complement~ {i}, t + If[i < m, 2^i, 0]], {i, s}]]][Length[s]];
T[n_] := CoefficientList[b[Range[n], 0], x];
Table[T[n], {n, 0, 7}] // Flatten (* Jean-François Alcover, Feb 13 2023, after Alois P. Heinz *)
A226968
Number of labeled octopi with n nodes such that each tentacle has an odd number of nodes.
Original entry on oeis.org
0, 1, 1, 8, 30, 264, 1920, 20880, 226800, 3064320, 43908480, 722131200, 12773376000, 249559833600, 5236924492800, 118911189196800, 2883421981440000, 74715282690048000, 2054450584682496000, 59855791774851072000, 1839882143683584000000
Offset: 0
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nn=20;f[x_]:=x/(1-x^2);Range[0,nn]!CoefficientList[Series[Log[1/(1-f[x])],{x,0,nn}],x]
A079638
Matrix product of unsigned Lah-triangle |A008297(n,k)| and unsigned Stirling1-triangle |A008275(n,k)|.
Original entry on oeis.org
1, 3, 1, 14, 9, 1, 90, 83, 18, 1, 744, 870, 275, 30, 1, 7560, 10474, 4275, 685, 45, 1, 91440, 143892, 70924, 14805, 1435, 63, 1, 1285200, 2233356, 1274196, 324289, 41160, 2674, 84, 1, 20603520, 38769840, 24870572, 7398972, 1151409, 98280, 4578
Offset: 1
Triangle begins
1;
3, 1;
14, 9, 1;
90, 83, 18, 1;
744, 870, 275, 30, 1;
7560, 10474, 4275, 685, 45, 1;
...
- Michael De Vlieger, Table of n, a(n) for n = 1..1225 (rows n = 1..50, flattened).
- William Keith, Rishi Nath, and James Sellers, On simultaneous (s, s+t, s+2t, ...)-core partitions, arXiv:2508.00074 [math.CO], 2025. See p. 3.
-
# The function BellMatrix is defined in A264428.
# Adds (1, 0, 0, 0, ..) as column 0.
BellMatrix(n -> n!*(2^(n+1)-1), 9); # Peter Luschny, Jan 26 2016
-
BellMatrix[f_, len_] := With[{t = Array[f, len, 0]}, Table[BellY[n, k, t], {n, 0, len - 1}, {k, 0, len - 1}]];
B = BellMatrix[Function[n, n! (2^(n + 1) - 1)], rows = 12];
Table[B[[n, k]], {n, 2, rows}, {k, 2, n}] // Flatten (* Jean-François Alcover, Jun 28 2018, after Peter Luschny *)
A328055
Expansion of e.g.f. -log(1 - x / (1 - x)^2).
Original entry on oeis.org
0, 1, 5, 32, 270, 2904, 38400, 605520, 11113200, 232888320, 5488560000, 143704108800, 4138573824000, 130020673305600, 4425201196416000, 162194862064435200, 6369479157000960000, 266808274486161408000, 11874724379464826880000, 559591797303082672128000
Offset: 0
For n=2, the 3 labeled octopuses are the following, and there are 2+2+1 ways to choose one element from each branch:
O-1-2;
O-2-1;
1-O-2. - _Enrique Navarrete_, Oct 29 2023
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[0] cat [Factorial(n - 1)*(Lucas(2*n)-2):n in [1..20]]; // Marius A. Burtea, Oct 03 2019
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nmax = 19; CoefficientList[Series[-Log[1 - x/(1 - x)^2], {x, 0, nmax}], x] Range[0, nmax]!
Join[{0}, Table[(n - 1)! (LucasL[2 n] - 2), {n, 1, 19}]]
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my(x='x+O('x^20)); concat(0, Vec(serlaplace(-log(1 - x / (1 - x)^2)))) \\ Michel Marcus, Oct 03 2019
A355257
Array read by ascending antidiagonals. A(n, k) = k! * [x^k] log((1 - x) / (1 - 2*x)) / (1 - x)^n, for 0 <= k <= n.
Original entry on oeis.org
0, 0, 1, 0, 1, 3, 0, 1, 5, 14, 0, 1, 7, 29, 90, 0, 1, 9, 50, 206, 744, 0, 1, 11, 77, 406, 1774, 7560, 0, 1, 13, 110, 714, 3804, 18204, 91440, 0, 1, 15, 149, 1154, 7374, 41028, 218868, 1285200, 0, 1, 17, 194, 1750, 13144, 85272, 506064, 3036144, 20603520
Offset: 0
Table A(n, k) begins:
[0] 0, 1, 3, 14, 90, 744, 7560, 91440, 1285200, ... A029767
[1] 0, 1, 5, 29, 206, 1774, 18204, 218868, 3036144, ... A103213
[2] 0, 1, 7, 50, 406, 3804, 41028, 506064, 7084656, ... A355171
[3] 0, 1, 9, 77, 714, 7374, 85272, 1102968, 15908400, ... A355372
[4] 0, 1, 11, 110, 1154, 13144, 164136, 2251920, 33923760, ... A355407
[5] 0, 1, 13, 149, 1750, 21894, 295500, 4320420, 68487120, ... A355414
[6] 0, 1, 15, 194, 2526, 34524, 502644, 7838928, 131198544, ...
[7] 0, 1, 17, 245, 3506, 52054, 814968, 13543704, 239548176, ...
-
egf := n -> log((1 - x)/(1 - 2*x))/(1 - x)^n:
ser := n -> series(egf(n), x, 22):
row := n -> seq(k!*coeff(ser(n), x, k), k = 0..8):
seq(print(row(n)), n = 0..8);
# Alternative:
A := (n, k) -> add(k!*binomial(k + n - 1, k - j - 1)/(j + 1), j = 0..k-1):
seq(print(seq(A(n, k), k = 0..8)), n = 0..7);
-
A[0, 0] = 0; A[n_, k_] := k! * Binomial[n+k-1, k - 1] * HypergeometricPFQ[{1 - k, 1, 1}, {2, n + 1}, -1];
Table[A[n, k], {n, 0, 8}, {k, 0, 8}] // TableForm
Showing 1-10 of 15 results.
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