Mohammad Hadi Shekarriz - cp's OEIS frontend

User: Mohammad Hadi Shekarriz

Mohammad Hadi Shekarriz has authored 3 sequences.

A309784 T(n,k) is the number of non-equivalent distinguishing coloring partitions of the cycle on n vertices with exactly k parts. Regular triangle read by rows, n >= 1, 1 <= k <= n.

0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 4, 2, 1, 0, 1, 8, 10, 3, 1, 0, 1, 25, 32, 16, 3, 1, 0, 4, 62, 129, 84, 27, 4, 1, 0, 7, 176, 468, 433, 171, 37, 4, 1, 0, 18, 470, 1806, 2260, 1248, 338, 54, 5, 1, 0, 31, 1311, 6780, 11515, 8388, 3056, 590, 70, 5, 1, 0, 70, 3620, 25917, 58312, 56065, 26695, 6907, 1014, 96, 6, 1

Offset: 1

Mohammad Hadi Shekarriz, Aug 17 2019

The cycle graph is defined for n>=3; extended to n=1,2 using the closed form.
A vertex-coloring of a graph G is called distinguishing if it is only preserved by the identity automorphism of G. This notion is considered in the subject of symmetry breaking of simple (finite or infinite) graphs. A distinguishing coloring partition of a graph G is a partition of the vertices of G such that it induces a distinguishing coloring for G. We say two distinguishing coloring partitions P1 and P2 of G are equivalent if there is a nontrivial automorphism of G which maps P1 onto P2. Given a graph G, we use the notation psi_k(G) to denote the number of non-equivalent distinguishing coloring partitions of G with exactly k parts. For n>=3, this sequence gives T(n,k) = psi_k(C_n), i.e., the number of non-equivalent distinguishing coloring partitions of the cycle C_n on n vertices with exactly k parts.
T(n,k) is the number of primitive (period n) n-bead bracelet structures which are not periodic palindromes using exactly k different colored beads. - Andrew Howroyd, Sep 20 2019

			The triangle begins:
  0;
  0,  0;
  0,  0,   1;
  0,  0,   1,    1;
  0,  0,   4,    2,    1;
  0,  1,   8,   10,    3,    1;
  0,  1,  25,   32,   16,    3,   1;
  0,  4,  62,  129,   84,   27,   4,  1;
  0,  7, 176,  468,  433,  171,  37,  4, 1;
  0, 18, 470, 1806, 2260, 1248, 338, 54, 5, 1;
  ...
For n=6, we can partition the vertices of C_6 into exactly 3 parts in 8 ways such that all these partitions induce distinguishing colorings for C_6 and that all the 8 partitions are non-equivalent. The partitions are as follows:
    { { 1 }, { 2 }, { 3, 4, 5, 6 } }
    { { 1 }, { 2, 3 }, { 4, 5, 6 } }
    { { 1 }, { 2, 3, 4, 6 }, { 5 } }
    { { 1 }, { 2, 3, 5 }, { 4, 6 } }
    { { 1 }, { 2, 3, 6 }, { 4, 5 } }
    { { 1 }, { 2, 4, 5 }, { 3, 6 } }
    { { 1, 2 }, { 3, 4 }, { 5, 6 } }
    { { 1, 2 }, { 3, 5 }, { 4, 6 } }
For n=6, the above 8 partitions can be written as the following 3 colored bracelet structures: ABCCCC, ABBCCC, ABBBCB, ABBCBC, ABBCCB, ABCBBC, AABBCC, AABCBC. - _Andrew Howroyd_, Sep 22 2019

Andrew Howroyd, Table of n, a(n) for n = 1..1275
B. Ahmadi, F. Alinaghipour and M. H. Shekarriz, Number of Distinguishing Colorings and Partitions, arXiv:1910.12102 [math.CO], 2019.
Mohammad Hadi Shekarriz, GAP Program

Column k=2 appears to be A011948.
Columns k=3..4 are A328038, A328039.
Row sums are A328035.
Cf. A107424, A152175, A152176, A276543, A276544, A285012, A285037, A309748, A309785.

\\ Ach is A304972 and R is A152175 as square matrices.
Ach(n)={my(M=matrix(n, n, i, k, i>=k)); for(i=3, n, for(k=2, n, M[i, k]=k*M[i-2, k] + M[i-2, k-1] + if(k>2, M[i-2, k-2]))); M}
R(n)={Mat(Col([Vecrev(p/y, n) | p<-Vec(intformal(sum(m=1, n, eulerphi(m) * subst(serlaplace(-1 + exp(sumdiv(m, d, y^d*(exp(d*x + O(x*x^(n\m)))-1)/d))), x, x^m))/x))]))}
T(n)={my(A=Ach(n), M=R(n), S=matrix(n, n, n, k, stirling(n, k, 2))); Mat(vectorv(n, n, sumdiv(n, d, moebius(d)*(M[n/d,] + A[n/d,])/2 - moebius(d)*(S[(n/d+1)\2, ] + S[n/d\2+1, ] + if((n-d)%2, A[(n/d+1)\2, ] + A[n/d\2+1, ]))/if(d%2, 2, 1) )))}
{ my(A=T(12)); for(n=1, #A, print(A[n, 1..n])) } \\ Andrew Howroyd, Oct 02 2019

T(n,k) = A276543(n,k) - A285037(n,k). - Andrew Howroyd, Sep 20 2019

T(10,6) corrected by Mohammad Hadi Shekarriz, Sep 28 2019

a(56)-a(78) from Andrew Howroyd, Sep 28 2019

A309748 The number of non-equivalent distinguishing coloring partitions of the path on n vertices (n>=1) with exactly k parts (k>=1). Regular triangle read by rows: the rows are indexed by n, the number of vertices of the path, and the columns are indexed by k, the number of parts.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 4, 4, 1, 0, 6, 14, 6, 1, 0, 16, 49, 37, 9, 1, 0, 28, 154, 182, 76, 12, 1, 0, 64, 496, 876, 542, 142, 16, 1, 0, 120, 1520, 3920, 3522, 1346, 242, 20, 1, 0, 256, 4705, 17175, 21392, 11511, 2980, 390, 25, 1, 0, 496, 14266, 73030, 123665, 89973, 32141, 5990, 595, 30, 1

Offset: 1

Mohammad Hadi Shekarriz, Aug 15 2019

A vertex-coloring of a graph G is called distinguishing if it is only preserved by the identity automorphism of G. This notion is considered in the subject of symmetry breaking of simple (finite or infinite) graphs. A distinguishing coloring partition of a graph G is a partition of the vertices of G such that it induces a distinguishing coloring for G. We say two distinguishing coloring partitions P1 and P2 of G are equivalent if there is a nontrivial automorphism of G which maps P1 onto P2. Given a graph G, we use the notation psi_k(G) to denote the number of non-equivalent distinguishing coloring partitions of G with at exactly k parts. For n>=1, this sequence gives T(n,k) = psi_k(P_n), i.e., the number of non-equivalent distinguishing coloring partitions of the path P_n on n vertices with exactly k parts.

Also, for n > 1 the number of reversible string structures of length n using exactly k different symbols that are not equivalent to their reversal (compare A284949). - Andrew Howroyd, Aug 15 2019

			The triangle begins:
  1;
  0,   1;
  0,   1,    1;
  0,   4,    4,     1;
  0,   6,   14,     6,     1;
  0,  16,   49,    37,     9,     1;
  0,  28,  154,   182,    76,    12,    1;
  0,  64,  496,   876,   542,   142,   16,   1;
  0, 120, 1520,  3920,  3522,  1346,  242,  20,  1;
  0, 256, 4705, 17175, 21392, 11511, 2980, 390, 25, 1;
  ...
----
For n=4, we can partition the vertices of P_4 into exactly 3 parts in 4 ways such that all these partitions induce distinguishing colorings for P_4 and that all the 4 partitions are non-equivalent. The partitions are as follows:
    { { 1 }, { 2 }, { 3, 4 } }
    { { 1 }, { 2, 3 }, { 4 } }
    { { 1 }, { 2, 4 }, { 3 } }
    { { 1, 4 }, { 2 }, { 3 } }

Andrew Howroyd, Table of n, a(n) for n = 1..1275
B. Ahmadi, F. Alinaghipour and M. H. Shekarriz, Number of Distinguishing Colorings and Partitions, arXiv:1910.12102 [math.CO], 2019.
Mohammad Hadi Shekarriz, GAP Program

Columns k=2..4 are A007179, A327610, A327611.
Row sums are A327612(n > 1).
Cf. A284949, A304972, A309635, A309784.

\\ Ach is A304972 as square matrix.
Ach(n)={my(M=matrix(n, n, i, k, i>=k)); for(i=3, n, for(k=2, n, M[i, k]=k*M[i-2, k] + M[i-2, k-1] + if(k>2, M[i-2, k-2]))); M}
T(n)={(matrix(n, n, i, k, stirling(i, k, 2) - 2*stirling((i+1)\2, k, 2)) + Ach(n))/2}
{ my(A=T(10)); A[1,1]=1; for(n=1, #A, print(A[n, 1..n])) } \\ Andrew Howroyd, Sep 18 2019

T(n,k) = A309635(n,k) - A309635(n,k-1) for k > 1.

T(n,k) = A284949(n,k) - Stirling2(ceiling(n/2), k) for n > 1. - Andrew Howroyd, Aug 15 2019

Terms a(56) and beyond from Andrew Howroyd, Sep 18 2019

A309635 The number of non-equivalent distinguishing coloring partitions of the path on n vertices (n>=1) with at most k parts (k>=1). Square array read by descending antidiagonals: the rows are indexed by n, the number of vertices of the path, and the columns are indexed by k, the number of parts.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 2, 4, 0, 1, 1, 2, 8, 6, 0, 1, 1, 2, 9, 20, 16, 0, 1, 1, 2, 9, 26, 65, 28, 0, 1, 1, 2, 9, 27, 102, 182, 64, 0, 1, 1, 2, 9, 27, 111, 364, 560, 120, 0, 1, 1, 2, 9, 27, 112, 440, 1436, 1640, 256, 0

Offset: 1

Mohammad Hadi Shekarriz, Aug 13 2019

A vertex-coloring of a graph G is called distinguishing if it is only preserved by the identity automorphism of G. This notion is considered in the subject of symmetry breaking of simple (finite or infinite) graphs. A distinguishing coloring partition of a graph G is a partition of the vertices of G such that it induces a distinguishing coloring for G. We say two distinguishing coloring partitions P1 and P2 of G are equivalent if there is a nontrivial automorphism of G which maps P1 onto P2. Given a graph G, we use the notation Psi_k(G) to denote the number of non-equivalent distinguishing coloring partitions of G with at most k parts. This sequence gives A(n,k) = Psi_k(P_n), i.e., the number of non-equivalent distinguishing coloring partitions of the path P_n on n vertices with at most k parts.

Note that, for any graph G, Psi_k(G) = Sum_{i<=k} psi_i(G), where psi_i(G) is the number of non-equivalent distinguishing coloring partitions of G with exactly i parts. For instance, here we have T(n,k) = Sum_{i<=k} A309748(n,i).

			Table begins:
  ======================================================================
  n\k| 1    2     3      4      5      6      7      8      9     10
  ---+------------------------------------------------------------------
   1 | 1,   1,    1,     1,     1,     1,     1,     1,     1,     1 ...
   2 | 0,   1,    1,     1,     1,     1,     1,     1,     1,     1 ...
   3 | 0,   1,    2,     2,     2,     2,     2,     2,     2,     2 ...
   4 | 0,   4,    8,     9,     9,     9,     9,     9,     9,     9 ...
   5 | 0,   6,   20,    26,    27,    27,    27,    27,    27,    27 ...
   6 | 0,  16,   65,   102,   111,   112,   112,   112,   112,   112 ...
   7 | 0,  28,  182,   364,   440,   452,   453,   453,   453,   453 ...
   8 | 0,  64,  560,  1436,  1978,  2120,  2136,  2137,  2137,  2137 ...
   9 | 0, 120, 1640,  5560,  9082, 10428, 10670, 10690, 10691, 10691 ...
  10 | 0, 256, 4961, 22136, 43528, 55039, 58019, 58409, 58434, 58435 ...
  ...
For n=4, we can partition the vertices of P_4 into at most 3 parts in 8 ways such that all these partitions induce distinguishing colorings for P_4 and that all the 8 partitions are non-equivalent. The partitions are as follows:
    { { 1 }, { 2 }, { 3, 4 } }
    { { 1 }, { 2, 3 }, { 4 } }
    { { 1 }, { 2, 4 }, { 3 } }
    { { 1, 4 }, { 2 }, { 3 } }
    { { 1 }, { 2, 3, 4 } }
    { { 1, 2 }, { 3, 4 } }
    { { 1, 2, 4 }, { 3 } }
    { { 1, 3 }, { 2, 4 } }

B. Ahmadi, F. Alinaghipour and M. H. Shekarriz, Number of Distinguishing Colorings and Partitions, arXiv:1910.12102 [math.CO], 2019.
Mohammad Hadi Shekarriz, GAP code

Column k=2 is A007179(n > 1).

Cf. A284949, A309748.

T(n, k) = Sum_{i=1..k} A309748(n,i).

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User: Mohammad Hadi Shekarriz

A309784 T(n,k) is the number of non-equivalent distinguishing coloring partitions of the cycle on n vertices with exactly k parts. Regular triangle read by rows, n >= 1, 1 <= k <= n.

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A309748 The number of non-equivalent distinguishing coloring partitions of the path on n vertices (n>=1) with exactly k parts (k>=1). Regular triangle read by rows: the rows are indexed by n, the number of vertices of the path, and the columns are indexed by k, the number of parts.

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PARI

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A309635 The number of non-equivalent distinguishing coloring partitions of the path on n vertices (n>=1) with at most k parts (k>=1). Square array read by descending antidiagonals: the rows are indexed by n, the number of vertices of the path, and the columns are indexed by k, the number of parts.

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Author

Keywords

Comments

Examples

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Crossrefs

Formula