A102087
Column 1 of triangular matrix A102086, which shifts upward to exclude the main diagonal under matrix square.
Original entry on oeis.org
0, 2, 4, 20, 156, 1664, 22684, 378572, 7504640, 172785512, 4540756252, 134330010172, 4423176368332, 160596613105384, 6378859853838480, 275308217428662672, 12836003750434047344, 643227594173121801096
Offset: 0
-
T[n_, n_] := n+1; T[n_, k_] /; k>n = 0; T[n_, k_] /; k == n-1 := n^2; T[n_, k_] := T[n, k] = Coefficient[1-Sum[T[i, k]*x^i*Product[1-(j+k)*x, {j, 1, i-k+1}], {i, k, n-1}], x, n]; a[n_] := T[n, 1]; Table[a[n], {n, 0, 17} ] (* Jean-François Alcover, Dec 15 2014 *)
-
{a(n)=local(A=matrix(2,2),B);A[1,1]=1; for(m=2,n+1,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=j,if(j==1,B[i,j]=(A^2)[i-1,1], B[i,j]=(A^2)[i-1,j]));));A=B); return(A[n+1,2])}
A102088
Row sums of triangular matrix A102086, which shifts upward to exclude the main diagonal under matrix square.
Original entry on oeis.org
1, 3, 10, 49, 367, 3850, 52173, 868614, 17199370, 395757887, 10396896795, 307511681367, 10124396776169, 367567456615441, 14598938725992903, 630060602243145513, 29375322688053255480, 1472008290120323375502
Offset: 0
-
{a(n)=local(A=matrix(2,2),B);A[1,1]=1; for(m=2,n+1,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=j,if(j==1,B[i,j]=(A^2)[i-1,1], B[i,j]=(A^2)[i-1,j]));));A=B); return(sum(k=0,n,A[n+1,k+1]))}
A082161
Number of deterministic completely defined initially connected acyclic automata with 2 inputs and n transient unlabeled states (and a unique absorbing state).
Original entry on oeis.org
1, 3, 16, 127, 1363, 18628, 311250, 6173791, 142190703, 3737431895, 110577492346, 3641313700916, 132214630355700, 5251687490704524, 226664506308709858, 10568175957745041423, 529589006347242691143, 28395998790096299447521
Offset: 1
a(2)=3 since the following transition diagrams represent all three initially connected acyclic automata with two input letters x and y, two transient states 1 (initial) and 2 and the absorbing state 0:
1 == x, y==> 2 == x, y ==> 0 == x, y ==> 0, 1 -- x --> 2 == x, y ==> 0 == x, y ==> 0
1 -- y --> 0
and the last one with x and y interchanged.
- Roland Bacher and Christophe Reutenauer, The number of right ideals of given codimension over a finite field, in Noncommutative Birational Geometry, Representations and Combinatorics, edited by Arkady. Berenstein and Vladimir. Retakha, Contemporary Mathematics, Vol. 592, 2013.
- Vaclav Kotesovec, Table of n, a(n) for n = 1..350
- David Callan, A determinant of Stirling cycle numbers counts unlabeled acyclic single-source automata, arXiv:0704.0004 [math.CO], 2007.
- Manosij Ghosh Dastidar and Michael Wallner, Asymptotics of relaxed k-ary trees, arXiv:2404.08415 [math.CO], 2024. See p. 1.4.
- Andrew Elvey Price, Wenjie Fang, and Michael Wallner, Compacted binary trees admit a stretched exponential, arXiv:1908.11181 [math.CO], 2019-2020; J. Combin. Theory Ser. A 177 (2021), Paper No. 105306, 40 pp.
- Antoine Genitrini, Bernhard Gittenberger, Manuel Kauers and Michael Wallner, Asymptotic enumeration of compacted binary trees of bounded right height, arXiv:1703.10031 [math.CO], 2017; J. Combin. Theory Ser. A 172 (2020), 105177, 49 pp.
- Valery A. Liskovets, Exact enumeration of acyclic automata, Proc. 15th Conf. "Formal Power Series and Algebr. Combin. (FPSAC'03)", 2003.
- Valery A. Liskovets, Exact enumeration of acyclic deterministic automata, Discrete Appl. Math., 154, No.3 (2006), 537-551.
- Fedor Petrov, On a generating function and vector ν of length n, answer to question on MathOverflow (2024).
- Michael Wallner, A bijection of plane increasing trees with relaxed binary trees of right height at most one, arXiv:1706.07163 [math.CO], 2017-2018; Theoret. Comput. Sci. 755 (2019), 1-12.
-
a[n_]:= a[n]= If[n==0, 1, Coefficient[1-Sum[a[k]*x^k*Product[1-j*x, {j, 1, k+1}], {k, 0, n-1}], x, n]];
Table[a[n], {n, 18}] (* Jean-François Alcover, Dec 15 2014, after Paul D. Hanna *)
-
{a(n)=if(n==0,1,polcoeff(1-sum(k=0,n-1,a(k)*x^k*prod(j=1,k+1,1-j*x+x*O(x^n))),n))} \\ Paul D. Hanna, Jan 07 2005
-
{a(n)=local(A);if(n<1,0,A=x+x*O(x^n); for(k=0,n,A+=polcoeff(A,k)*x^k*(1-prod(i=1,k+1,1-i*x))); polcoeff(A,n))} /* Michael Somos, Jan 16 2005 */
-
upto(n) = my(v=vector(n+1, i, i==1)); for(i=1, n, for(j=i+1, n+1, v[j] += i*v[j-1])); v[2..#v] \\ Mikhail Kurkov, Oct 25 2024
-
from functools import cache
@cache
def b(n, k):
if n == 0: return k + 1
return sum(b(j, k)*b(n-j-1, k+j) for j in range(n))
def A082161(n): return b(n, 0)
print([A082161(n) for n in range(1, 19)]) # G. C. Greubel, Jan 18 2024
A102098
Triangular matrix, read by rows, that satisfies: T(n,k) = [T^3](n-1,k) when n>k>=0, with T(n,n) = (n+1).
Original entry on oeis.org
1, 1, 2, 7, 8, 3, 139, 152, 27, 4, 5711, 6200, 999, 64, 5, 408354, 442552, 69687, 3904, 125, 6, 45605881, 49399320, 7724835, 416704, 11375, 216, 7, 7390305396, 8003532512, 1248465852, 66464960, 1725875, 27432, 343, 8, 1647470410551
Offset: 0
Rows of T begin:
[1],
[1,2],
[7,8,3],
[139,152,27,4],
[5711,6200,999,64,5],
[408354,442552,69687,3904,125,6],
[45605881,49399320,7724835,416704,11375,216,7],
[7390305396,8003532512,1248465852,66464960,1725875,27432,343,8],...
Matrix cube T^3 equals T excluding the main diagonal:
[1],
[7,8],
[139,152,27],
[5711,6200,999,64],
[408354,442552,69687,3904,125],...
-
{T(n,k)=local(A=matrix(1,1),B);A[1,1]=1; for(m=2,n+1,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=j,if(j==1,B[i,j]=(A^3)[i-1,1], B[i,j]=(A^3)[i-1,j]));));A=B);return(A[n+1,k+1])}
A102316
Triangle, read by rows, where T(n,k) = T(n,k-1) + (k+1)*T(n-1,k) for n>k>0, T(n,0)=1 and T(n,n) = T(n,n-1) for n>=0.
Original entry on oeis.org
1, 1, 1, 1, 3, 3, 1, 7, 16, 16, 1, 15, 63, 127, 127, 1, 31, 220, 728, 1363, 1363, 1, 63, 723, 3635, 10450, 18628, 18628, 1, 127, 2296, 16836, 69086, 180854, 311250, 311250, 1, 255, 7143, 74487, 419917, 1505041, 3683791, 6173791, 6173791, 1, 511, 21940
Offset: 0
T(5,2) = 220 = 1*1 + 2*15 + 3*63 = 1*T(4,0) + 2*T(4,1) + 3*T(4,2).
T(5,2) = 220 = 31 + 3*63 = T(5,1) + (2+1)*T(4,2).
T(5,3) = 728 = 220 + 4*127 = T(5,2) + (3+1)*T(4,3).
Rows begin:
[1],
[1,1],
[1,3,3],
[1,7,16,16],
[1,15,63,127,127],
[1,31,220,728,1363,1363],
[1,63,723,3635,10450,18628,18628],
[1,127,2296,16836,69086,180854,311250,311250],
[1,255,7143,74487,419917,1505041,3683791,6173791,6173791],...
A102916
Triangle, read by rows, where the antidiagonals are formed by interleaving the rows of triangle A102098 with the rows of its matrix square (A102920).
Original entry on oeis.org
1, 1, 2, 1, 4, 3, 3, 8, 9, 4, 7, 40, 27, 16, 5, 36, 152, 189, 64, 25, 6, 139, 1128, 999, 576, 125, 36, 7, 1036, 6200, 9720, 3904, 1375, 216, 49, 8, 5711, 61120, 69687, 47040, 11375, 2808, 343, 64, 9, 56355, 442552, 857466, 416704, 163500, 27432, 5145, 512
Offset: 0
Rows begin:
[1],
[1,2],
[1,4,3],
[3,8,9,4],
[7,40,27,16,5],
[36,152,189,64,25,6],
[139,1128,999,576,125,36,7],
[1036,6200,9720,3904,1375,216,49,8],
[5711,61120,69687,47040,11375,2808,343,64,9],...
The antidiagonals are formed by interleaving the
rows of triangle A102098:
[1],
[1,2],
[7,8,3],
[139,152,27,4],...
with the rows of the matrix square of A102098,
which is triangle A102920:
[1],
[3,4],
[36,40,9],
[1036,1128,189,16],...
G.f. for Column 0 (A102917): 1 = 1*(1-x) + 1*x*(1-x)
+ 1*x^2*(1-x)(1-2x) + 3*x^3*(1-x)(1-2x)
+ 7*x^4*(1-x)(1-2x)(1-3x) + 36*x^5*(1-x)(1-2x)(1-3x) +...
+ A082162(n)*x^(2n)*(1-x)(1-2x)*..*(1-(n+1)x)
+ A102921(n)*x^(2n+1)*(1-x)(1-2x)*..*(1-(n+1)x) + ...
G.f. for Column 1 (A102918): 2 = 2*(1-2x) + 4*x*(1-2x)
+ 8*x^2*(1-2x)(1-3x) + 40*x^3*(1-2x)(1-3x)
+ 152*x^4*(1-2x)(1-3x)(1-4x) + 1128*x^5*(1-2x)(1-3x)(1-4x) +...
+ T(2n+1,1)*x^(2n)*(1-2x)(1-3x)*..*(1-(n+2)x)
+ T(2n+2,1)*x^(2n+1)*(1-2x)(1-3x)*..*(1-(n+2)x) + ...
A102101
Triangular matrix, read by rows, that satisfies: T(n,k) = [T^4](n-1,k) when n>k>=0, with T(n,n) = (n+1).
Original entry on oeis.org
1, 1, 2, 15, 16, 3, 1000, 1040, 81, 4, 189035, 196080, 14175, 256, 5, 79278446, 82196224, 5866992, 94464, 625, 6, 63263422646, 65585046960, 4667640795, 73281280, 419375, 1296, 7, 86493299281972, 89664824687968, 6376139907030
Offset: 0
Rows of T begin:
[1],
[1,2],
[15,16,3],
[1000,1040,81,4],
[189035,196080,14175,256,5],
[79278446,82196224,5866992,94464,625,6],
[63263422646,65585046960,4667640795,73281280,419375,1296,7].
Matrix fourth power T^4 equals T excluding the main diagonal:
[1],
[15,16],
[1000,1040,81],
[189035,196080,14175,256],
[79278446,82196224,5866992,94464,625],...
-
{T(n,k)=local(A=matrix(1,1),B);A[1,1]=1; for(m=2,n+1,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=j,if(j==1,B[i,j]=(A^4)[i-1,1], B[i,j]=(A^4)[i-1,j]));));A=B);return(A[n+1,k+1])}
A102320
Triangular matrix, read by rows, that satisfies: T(n,k) = [T^2](n-1,k) when n>k>=0, with T(n,n) = (2*n+1).
Original entry on oeis.org
1, 1, 3, 4, 9, 5, 33, 72, 25, 7, 436, 945, 300, 49, 9, 8122, 17568, 5425, 784, 81, 11, 197920, 427770, 130700, 18081, 1620, 121, 13, 6007205, 12979080, 3947050, 535864, 45441, 2904, 169, 15, 219413116, 473981445, 143812400, 19348042, 1599588, 95953
Offset: 0
Rows of T begin:
[1],
[1,3],
[4,9,5],
[33,72,25,7],
[436,945,300,49,9],
[8122,17568,5425,784,81,11],
[197920,427770,130700,18081,1620,121,13],
[6007205,12979080,3947050,535864,45441,2904,169,15],...
Matrix square T^2 equals T excluding the main diagonal:
[1],
[4,9],
[33,72,25],
[436,945,300,49],
[8122,17568,5425,784,81],...
-
{T(n,k)=local(A=Mat(1),B); for(m=2,n+1,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=2*j-1,if(j==1,B[i,j]=(A^2)[i-1,1], B[i,j]=(A^2)[i-1,j]));));A=B);return(A[n+1,k+1])}
A106208
Triangular matrix T, read by rows, that satisfies: [T^-1](n,k) = -(k+1)*T(n-1,k) when (n-1)>=k>=0, with T(n,n) = 1 and T(n+1,n) = (n+1) for n>=0.
Original entry on oeis.org
1, 1, 1, 3, 2, 1, 16, 10, 3, 1, 127, 78, 21, 4, 1, 1363, 832, 216, 36, 5, 1, 18628, 11342, 2901, 460, 55, 6, 1, 311250, 189286, 48081, 7456, 840, 78, 7, 1, 6173791, 3752320, 949800, 145660, 15955, 1386, 105, 8, 1, 142190703, 86392756, 21826470, 3327340
Offset: 0
Triangle T begins:
1;
1,1;
3,2,1;
16,10,3,1;
127,78,21,4,1;
1363,832,216,36,5,1;
18628,11342,2901,460,55,6,1;
311250,189286,48081,7456,840,78,7,1;
6173791,3752320,949800,145660,15955,1386,105,8,1; ...
Matrix inverse T^-1 begins:
1;
-1,1;
-1,-2,1;
-3,-4,-3,1;
-16,-20,-9,-4,1;
-127,-156,-63,-16,-5,1;
-1363,-1664,-648,-144,-25,-6,1;
-18628,-22684,-8703,-1840,-275,-36,-7,1; ...
where [T^-1](n,k) = -(k+1)*T(n-1,k) when (n-1)>=k>=0.
G.f. for column 0: 1 = 1(1-x) + 1*x*(1-x)(1-2x) +
3*x^2*(1-x)(1-2x)(1-3x) + ... +
T(n,0)*x^n*(1-x)(1-2x)(1-3x)*..*(1-(n+1)*x) + ...
G.f. for column 1: 1 = 1(1-2x) + 2*x*(1-2x)(1-3x) +
10*x^2*(1-2x)(1-3x)(1-4x) + ... +
T(n+1,1)*x^n*(1-2x)(1-3x)(1-4x)*..*(1-(n+2)*x) + ...
G.f. for column 2: 1 = 1(1-3x) + 3*x*(1-3x)(1-4x) +
21*x^2*(1-3x)(1-4x)(1-5x) + ... +
T(n+2,2)*x^n*(1-3x)(1-4x)(1-5x)*..*(1-(n+3)*x) + ...
-
T(n,k)=if(n
-
T(n,k)=local(A=matrix(1,1),B);A[1,1]=1; for(m=2,n+1,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=j,if(j==1,B[i,j]=(A^2)[i-1,1], B[i,j]=(A^2)[i-1,j]));));A=B);return(A[n+1,k+1]/(k+1))
A106210
Triangular matrix T, read by rows, that satisfies: [T^-1](n,k) = -k^2*T(n-2,k) when (n-2)>=k>=0, with T(n,n) = 1 and T(n+1,n) = (2*n+1) for n>=0.
Original entry on oeis.org
1, 1, 1, 3, 3, 1, 16, 16, 5, 1, 127, 127, 39, 7, 1, 1363, 1363, 416, 72, 9, 1, 18628, 18628, 5671, 967, 115, 11, 1, 311250, 311250, 94643, 16027, 1864, 168, 13, 1, 6173791, 6173791, 1876160, 316600, 36415, 3191, 231, 15, 1, 142190703, 142190703
Offset: 0
Triangle T begins:
1;
1,1;
3,3,1;
16,16,5,1;
127,127,39,7,1;
1363,1363,416,72,9,1;
18628,18628,5671,967,115,11,1;
311250,311250,94643,16027,1864,168,13,1;
6173791,6173791,1876160,316600,36415,3191,231,15,1; ...
Matrix inverse T^-1 begins:
1;
-1,1;
0,-3,1;
0,-1,-5,1;
0,-3,-4,-7,1;
0,-16,-20,-9,-9,1;
0,-127,-156,-63,-16,-11,1;
0,-1363,-1664,-648,-144,-25,-13,1;
0,-18628,-22684,-8703,-1840,-275,-36,-15,1; ...
where [T^-1](n,k) = -k^2*T(n-2,k) when (n-2)>=k>=0.
G.f. for column 0: 1/(1-0x) = 1*(1-1x) + 1*x*(1-1x)(1-2x) +
3*x^2*(1-1x)(1-2x)(1-3x) + 16*x^3*(1-1x)(1-2x)(1-3x)(1-4x) + ...
+ T(n,0)*x^n*(1-1x)(1-2x)*..*(1-(n+1)*x) + ...
G.f. for column 1: 1/(1-1x) = 1*(1-2x) + 3*x*(1-2x)(1-3x) +
16*x^2*(1-2x)(1-3x)(1-4x) + 127*x^3*(1-2x)(1-3x)(1-4x)(1-5x) + ...
+ T(n+1,1)*x^n*(1-2x)(1-3x)*..*(1-(n+2)*x) + ...
G.f. for column 2: 1/(1-2x) = 1*(1-3x) + 5*x*(1-3x)(1-4x) +
39*x^2*(1-3x)(1-4x)(1-5x) + 416*x^3*(1-3x)(1-4x)(1-5x)(1-6x) + ...
+ T(n+2,2)*x^n*(1-3x)(1-4x)*..*(1-(n+3)*x) + ...
-
T(n,k)=if(n
-
T(n,k)=local(A=matrix(1,1),B);A[1,1]=1; for(m=2,n+2,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=j,if(j==1,B[i,j]=(A^2)[i-1,1], B[i,j]=(A^2)[i-1,j]));));A=B); return(if(k==0,if(n==0,1,A[n+1,k+1]),A[n+1,k]/k^2))
Showing 1-10 of 11 results.
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