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 1-4 of 4 results.

A112340 Triangle read by rows of numbers b_{n,k}, n>=1, 1<=k<=n such that Product_{n,k} 1/(1-q^n t^k)^{b_{n,k}} = 1 + Sum_{i,j>=1} S_{i,j} q^i t^j where S_{i,j} are entries in the table A008277 (the inverse Euler transformation of the table of Stirling numbers of the second kind).

Original entry on oeis.org

1, 1, 0, 1, 2, 0, 1, 5, 3, 0, 1, 13, 16, 4, 0, 1, 28, 67, 34, 5, 0, 1, 60, 249, 229, 65, 6, 0, 1, 123, 853, 1265, 609, 107, 7, 0, 1, 251, 2787, 6325, 4696, 1376, 168, 8, 0, 1, 506, 8840, 29484, 31947, 14068, 2772, 244, 9, 0, 1, 1018, 27503, 131402, 199766, 124859, 36252
Offset: 1

Views

Author

Mike Zabrocki, Sep 05 2005; Aug 06 2006

Keywords

Comments

Row sums equal to A085686, second column = A084174 - 1
The number of set partitions of size n length k which are 'Lyndon,' that is, since all set partitions are isomorphic to sequences of atomic set partitions (A087903), those which are smallest of all rotations of these sequences in lex order (with respect to some ordering on the atomic set partitions) are Lyndon. 1; 1, 0; 1, 2, 0; 1, 5, 3, 0; 1, 13, 16, 4, 0;

Examples

			There are 6 set partitions of size 4 and length 3, {12|3|4}, {13|2|4}, {14|2|3}, {1|23|4}, {1|24|3}, {1|2|34} and the sequences the correspond to are ({12},{1},{1}), ({13|2}, {1}), ({14|2|3}), ({1},{12},{1}), ({1},{13|2}), ({1},{1},{12}). Now there are three {({12},{1},{1}), ({1},{12},{1}), ({1},{1},{12})} that are rotations of each other and ({1}, {1}, {12}) is the smallest of these, {({13|2}, {1}), ({1},{13|2})} are rotations of each other and ({1},{13|2}) is the smallest and ({14|2|3}) is atomic and all atomic s.p. are Lyndon. Hence {1|2|34}, {1|24|3}, {14|2|3} are Lyndon and a(4,3) = 3
Triangle begins:
  1;
  1,  0;
  1,  2,  0;
  1,  5,  3,  0;
  1, 13, 16,  4, 0;
  1, 28, 67, 34, 5, 0;
  ...
		

Crossrefs

Programs

  • Maple
    EULERitable:=proc(tbl) local ser,out,i,j,tmp; ser:=1+add(add(q^i*t^j*tbl[i][j], j=1..nops(tbl[i])), i=1..nops(tbl)); out:=[]; for i from 1 to nops(tbl) do tmp:=coeff(ser,q,i); ser:=expand(ser*mul(add((-q^i*t^j)^k*choose(abs(coeff(tmp,t,j)),k),k=0..nops(tbl)/i), j = 1..degree(tmp,t))); ser:=subs({seq(q^j=0,j=nops(tbl)+1..degree(ser,q))},ser); out:=[op(out),[seq(abs(coeff(tmp,t,j)), j=1..degree(tmp,t))]]; end do; out; end: EULERitable([seq([seq(combinat[stirling2](n,k),k=1..n)],n=1..10)]);
  • Mathematica
    nmax = 11; b[n_, k_] /; k < 1 || k > n = 0;
    coes[m_] := Product[1/(1 - q^n t^k)^b[n, k], {n, 1, m}, {k, 1, m}] - 1 - Sum[ StirlingS2[i, j] q^i t^j, {i, 1, m}, {j, 1, m}] + O[t]^m + O[q]^m // Normal // CoefficientList[#, {t, q}]&;
    sol[1] = {b[1, 1] -> 1};
    Do[sol[m] = Solve[Thread[(coes[m] /. sol[m - 1]) == 0]], {m, 2, nmax + 1}];
    bb = Flatten[Table[sol[m], {m, 1, nmax + 1}]];
    Table[b[n, k] /. bb, {n, 1, nmax}, {k, 1, n}] // Flatten (* Jean-François Alcover, Dec 11 2017 *)

A112339 Triangle read by rows of numbers b_{n,k}, n >= 2, 1 <= k < n such that (1/(1-q*t))*Product_{n,k} 1/(1 - q^n*t^k)^b_{n,k} = Sum_{i,j>=1} S_{i,j} q^i*t^j where S_{i,j} are entries in the table A008277 (the inverse Euler transformation of the table of Stirling numbers of the second kind).

Original entry on oeis.org

1, 1, 2, 1, 5, 3, 1, 13, 16, 4, 1, 28, 67, 34, 5, 1, 60, 249, 229, 65, 6, 1, 123, 853, 1265, 609, 107, 7, 1, 251, 2787, 6325, 4696, 1376, 168, 8, 1, 506, 8840, 29484, 31947, 14068, 2772, 244, 9, 1, 1018, 27503, 131402, 199766, 124859, 36252, 5118, 345, 10
Offset: 2

Views

Author

Mike Zabrocki, Sep 05 2005

Keywords

Comments

Row sums equal to A085686 second column = A084174 - 1.

Examples

			Triangle begins:
  1;
  1,  2;
  1,  5,  3;
  1, 13, 16,  4;
  ...
		

Crossrefs

Programs

  • Maple
    EULERitable:=proc(tbl) local ser,out,i,j,tmp; ser:=1+add(add(q^i*t^j*tbl[i][j], j=1..nops(tbl[i])), i=1..nops(tbl)); out:=[]; for i from 1 to nops(tbl) do tmp:=coeff(ser,q,i); ser:=expand(ser*mul(add((-q^i*t^j)^k*choose(abs(coeff(tmp,t,j)),k),k=0..nops(tbl)/i), j = 1..degree(tmp,t))); ser:=subs({seq(q^j=0,j=nops(tbl)+1..degree(ser,q))},ser); out:=[op(out),[seq(abs(coeff(tmp,t,j)), j=1..degree(tmp,t))]]; end do; out; end: EULERitable([seq([seq(combinat[stirling2](n,k),k=1..n)],n=1..11)]);

A131087 Triangle read by rows: T(n,k) = 2*binomial(n,k) - (1 + (-1)^(n-k))/2 (0 <= k <= n).

Original entry on oeis.org

1, 2, 1, 1, 4, 1, 2, 5, 6, 1, 1, 8, 11, 8, 1, 2, 9, 20, 19, 10, 1, 1, 12, 29, 40, 29, 12, 1, 2, 13, 42, 69, 70, 41, 14, 1, 1, 16, 55, 112, 139, 112, 55, 16, 1, 2, 17, 72, 167, 252, 251, 168, 71, 18, 1, 1, 20, 89, 240, 419, 504, 419, 240, 89, 20, 1, 2, 21, 110, 329, 660, 923, 924
Offset: 0

Views

Author

Gary W. Adamson, Jun 14 2007

Keywords

Comments

Row sums = A084174: (1, 3, 6, 14, 29, ...).
2*A007318 - A128174 as infinite lower triangular matrices. - Emeric Deutsch, Jun 21 2007

Examples

			First few rows of the triangle:
  1;
  2,  1;
  1,  4,  1;
  2,  5,  6,  1;
  1,  8, 11,  8,  1;
  2,  9, 20, 19, 10,  1;
  1, 12, 29, 40, 29, 12,  1;
  ...
		

Crossrefs

Programs

  • Maple
    T := proc (n, k) options operator, arrow; 2*binomial(n, k)-1/2-(1/2)*(-1)^(n-k) end proc; for n from 0 to 11 do seq(T(n, k), k = 0 .. n) end do; # yields sequence in triangular form - Emeric Deutsch, Jun 21 2007

Formula

G.f.: G(t,z) = (1 + z - tz - 2z^2 + 2tz^3)/((1-z^2)*(1-tz)*(1-z-tz)). - Emeric Deutsch, Jun 21 2007

Extensions

More terms from Emeric Deutsch, Jun 21 2007

A134520 Triangle read by rows: A007318 + A128174 - A000012 as infinite lower triangular matrices.

Original entry on oeis.org

1, 0, 1, 1, 1, 1, 0, 3, 2, 1, 1, 3, 6, 3, 1, 0, 5, 9, 10, 4, 1, 1, 5, 15, 19, 15, 5, 1, 0, 7, 20, 35, 34, 21, 6, 1, 1, 7, 28, 55, 70, 55, 28, 7, 1, 0, 9, 35, 84, 125, 126, 83, 36, 8, 1, 1, 9, 45, 119, 210, 251, 210, 119, 45, 9, 1, 0, 11, 54, 165, 329, 462, 461, 330, 164, 55, 10, 1
Offset: 0

Views

Author

Gary W. Adamson, Oct 29 2007

Keywords

Comments

Row sums = A084174: (1, 1, 3, 6, 14, 29, 61, ...).

Examples

			First few rows of the triangle:
  1;
  0,  1;
  1,  1,  1;
  0,  3,  2,  1;
  1,  3,  6,  3,  1;
  0,  5,  9, 10,  4,  1;
  1,  5, 15, 19, 15,  5,  1;
  0,  7, 20, 35, 34, 21,  6,  1;
  1,  7, 28, 55, 70, 55, 28,  7,  1;
  ...
		

Crossrefs

Extensions

a(45) = 1 corrected and more terms from Georg Fischer, Jun 07 2023
Showing 1-4 of 4 results.