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.

Previous Showing 11-20 of 644 results. Next

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 *)

A137650 Triangle read by rows, A008277 * A000012.

Original entry on oeis.org

1, 2, 1, 5, 4, 1, 15, 14, 7, 1, 52, 51, 36, 11, 1, 203, 202, 171, 81, 16, 1, 877, 876, 813, 512, 162, 22, 1, 4140, 4139, 4012, 3046, 1345, 295, 29, 1, 21147, 21146, 20891, 17866, 10096, 3145, 499, 37, 1, 115975, 115974, 115463
Offset: 1

Views

Author

Gary W. Adamson, Feb 01 2008

Keywords

Comments

Left column = Bell numbers (A000110) starting (1, 2, 5, 15, 52, 203, ...). Row sums = A005493(n+1): (1, 3, 10, 37, 151, 674, ...).
Corresponding to the generalized Stirling number triangle of first kind A049444. - Peter Luschny, Sep 18 2011

Examples

			First few rows of the triangle are
    1;
    2,   1;
    5,   4,   1;
   15,  14,   7,   1;
   52,  51,  36,  11,   1;
  203, 202, 171,  81,  16,   1;
  877, 876, 813, 512, 162,  22,   1;
  ...
		

Crossrefs

A similar triangle is A133611.

Programs

  • Maple
    A137650_row := proc(n) local k,i;
    add(add(combinat[stirling2](n, n-i), i=0..k)*x^(n-k-1),k=0..n-1);
    seq(coeff(%,x,k),k=0..n-1) end:
    seq(print(A137650_row(n)),n=1..7); # Peter Luschny, Sep 18 2011
  • Mathematica
    row[n_] := Table[StirlingS2[n, k], {k, 0, n}] // Reverse // Accumulate // Reverse // Rest;
    Array[row, 10] // Flatten (* Jean-François Alcover, Dec 07 2019 *)

Formula

A008277 * A000012 as infinite lower triangular matrices. Partial sums of A008277 rows starting from the right.

A039812 Triangle read by rows: matrix 4th power of the Stirling2 triangle A008277.

Original entry on oeis.org

1, 4, 1, 22, 12, 1, 154, 136, 24, 1, 1304, 1650, 460, 40, 1, 12915, 21904, 8550, 1160, 60, 1, 146115, 318521, 162904, 30590, 2450, 84, 1, 1855570, 5051988, 3246068, 789824, 86940, 4592, 112, 1, 26097835, 86910426, 68151304, 20606796, 2919504, 210924, 7896, 144, 1
Offset: 1

Views

Author

Christian G. Bower, Feb 15 1999

Keywords

Examples

			Triangle begins
      1;
      4,     1;
     22,    12,    1;
    154,   136,   24,    1;
   1304,  1650,  460,   40,  1;
  12915, 21904, 8550, 1160, 60, 1;
  ...
		

Crossrefs

Cf. A008277, A000307 (first column).

Programs

  • Mathematica
    Flatten[Table[SeriesCoefficient[(Exp[Exp[Exp[Exp[x]-1]-1]-1]-1)^k, {x,0,n}]  n!/k!, {n,9}, {k,n}]] (* Stefano Spezia, Sep 12 2022 *)

Formula

E.g.f. k-th column: (( exp(exp(exp(exp(x)-1)-1)-1)-1 )^k)/k!. [corrected by Seiichi Manyama, Feb 12 2022]

A049434 Stirling numbers of second kind: 8th column of Stirling2 triangle A008277.

Original entry on oeis.org

1, 36, 750, 11880, 159027, 1899612, 20912320, 216627840, 2141764053, 20415995028, 189036065010, 1709751003480, 15170932662679, 132511015347084, 1142399079991620, 9741955019900400, 82318282158320505, 690223721118368580, 5749622251945664950
Offset: 8

Views

Author

Keywords

References

Crossrefs

Programs

Formula

G.f.: x^8/product_{k=1..8} (1-k*x).
E.g.f.: ((exp(x)-1)^8)/8!.
a(n) = det(|s(i+8,j+7)|, 1 <= i,j <= n-8), where s(n,k) are Stirling numbers of the first kind. - Mircea Merca, Apr 06 2013

A049435 Stirling numbers of second kind: 10th column of Stirling2 triangle A008277.

Original entry on oeis.org

1, 55, 1705, 39325, 752752, 12662650, 193754990, 2758334150, 37112163803, 477297033785, 5917584964655, 71187132291275, 835143799377954, 9593401297313460, 108254081784931500, 1203163392175387500, 13199555372846848005, 143197070509423605675
Offset: 10

Views

Author

Keywords

References

Crossrefs

Programs

Formula

G.f.: x^10/Product_{k=1..10} (1-k*x).
E.g.f.: ((exp(x)-1)^10)/10!.
a(n) = det(|s(i+10,j+9)|, 1 <= i,j <= n-10), where s(n,k) are Stirling numbers of the first kind. - Mircea Merca, Apr 06 2013

A049447 Stirling numbers of second kind: 9th column of Stirling2 triangle A008277.

Original entry on oeis.org

1, 45, 1155, 22275, 359502, 5135130, 67128490, 820784250, 9528822303, 106175395755, 1144614626805, 12011282644725, 123272476465204, 1241963303533920, 12320068811796900, 120622574326072500, 1167921451092973005, 11201516780955125625, 106563273280541795575
Offset: 9

Views

Author

Keywords

References

Crossrefs

Programs

Formula

a(n)= A008277(n, 9).
G.f.: x^9/product_{k=1..9} (1-k*x).
E.g.f.: ((exp(x)-1)^9)/9!.
a(n) = det(|s(i+9,j+8)|, 1 <= i,j <= n-9), where s(n,k) are Stirling numbers of the first kind. - Mircea Merca, Apr 06 2013

A137597 Triangle read by rows: A008277 * A007318.

Original entry on oeis.org

1, 2, 1, 5, 5, 1, 15, 22, 9, 1, 52, 99, 61, 14, 1, 203, 471, 385, 135, 20, 1, 877, 2386, 2416, 1140, 260, 27, 1, 4140, 12867, 15470, 9156, 2835, 455, 35, 1, 21147, 73681, 102215, 72590, 28441, 6230, 742, 44, 1
Offset: 1

Views

Author

Gary W. Adamson, Jan 29 2008

Keywords

Comments

Row sums = A035009 starting (1, 3, 11, 47, 227, ...).

Examples

			First few rows of the triangle:
    1;
    2,   1;
    5,   5,   1;
   15,  22,   9,   1;
   52,  99,  61,  14,  1;
  203, 471, 385, 135, 20, 1;
  ...
		

Crossrefs

Programs

  • Maple
    T:= (n, k)-> add(Stirling2(n, j)*binomial(j-1, k-1), j=k..n):
    seq(seq(T(n, k), k=1..n), n=1..10);  # Alois P. Heinz, Sep 03 2019
  • Mathematica
    Table[Sum[StirlingS2[n, j]*Binomial[j - 1, k - 1], {j, k, n}], {n, 9}, {k, n}] // Flatten (* Michael De Vlieger, Aug 31 2023 *)

Formula

A008277 * A007318 as infinite lower triangular matrices.

A274712 a(n) = A008277(3*n-1,n) / (n*(n+1)/2) for n>=1, where A008277 are the Stirling numbers of the second kind.

Original entry on oeis.org

1, 5, 161, 14575, 2671669, 833607138, 397984073059, 270609861663900, 248922595132336125, 298037055910658382175, 450755158919281716609746, 840770855566250627155136090, 1896671776639253430025972662743, 5091278095597325836977485757711800, 16040729445423172146341201903726496024, 58625927208516621021861960954787323034320, 246047331971247756894582227572712664877434765, 1175344062721738572130662103242054758238706829325
Offset: 1

Views

Author

Paul D. Hanna, Jul 03 2016

Keywords

Crossrefs

Cf. A274713.

Programs

  • PARI
    {a(n) = polcoeff( 1/prod(k=1, n, 1-k*x +x*O(x^(2*n))), 2*n-1) / (n*(n+1)/2)}
    for(n=1, 20, print1(a(n), ", "))
    
  • PARI
    {a(n) = abs( stirling(3*n-1, n, 2) / (n*(n+1)/2) )}
    for(n=1, 20, print1(a(n), ", "))
    
  • PARI
    {a(n) = 1/n! * sum(k=0, n, (-1)^(n-k) * binomial(n, k) * k^(3*n-1)) / (n*(n+1)/2)}
    for(n=1, 20, print1(a(n), ", "))

Formula

a(n) = A274713(n) / (n*(n+1)/2), where A274713(n) is the number of partitions of a {3*n-1}-set into n nonempty subsets.
a(n) = 1/n! * Sum_{k=1..n} (-1)^(n-k) * binomial(n,k) * k^(3*n-1) / (n*(n+1)/2).
a(n) ~ sqrt(2) * 3^(3*n-1) * n^(2*n-7/2) / (exp(2*n) * c^n * (3-c)^(2*n-1) * sqrt(Pi*(1-c))), where c = -LambertW(-3*exp(-3)) = 0.1785606278779211... = -A226750. - Vaclav Kotesovec, Jul 06 2016

A055896 Exponential transform of Stirling2 triangle A008277.

Original entry on oeis.org

1, 1, 2, 1, 6, 5, 1, 14, 30, 15, 1, 30, 125, 150, 52, 1, 62, 450, 975, 780, 203, 1, 126, 1505, 5250, 7280, 4263, 877, 1, 254, 4830, 25515, 54600, 53998, 24556, 4140, 1, 510, 15125, 116550, 361452, 537138, 405174, 149040, 21147, 1, 1022, 46650
Offset: 1

Views

Author

Christian G. Bower, Jun 09 2000

Keywords

Examples

			Triangle begins
  1;
  1,   2;
  1,   6,   5;
  1,  14,  30,  15;
  1,  30, 125, 150,  52; ...
		

Crossrefs

Row sums give A000258.

Programs

  • Mathematica
    nn=8; a=Exp[x]-1; Drop[Map[Select[#, #>0&]&, Range[0,nn]! CoefficientList[Series[Exp[Exp[y a]-1], {x,0,nn}], {x,y}]], 1]//Grid (* Geoffrey Critzer, Sep 22 2013 *)

Formula

E.g.f.: A(x, y) = exp(exp(y*exp(x)-y)-1).

A061113 Concatenation of numbers in n-th row of triangle of Stirling numbers of second kind (A008277).

Original entry on oeis.org

1, 11, 131, 1761, 11525101, 1319065151, 163301350140211, 112796617011050266281, 12553025777069512646462361, 151193303410542525228275880750451
Offset: 1

Views

Author

Amarnath Murthy, Apr 21 2001

Keywords

References

  • Amarnath Murthy, A general result on the Smarandache Star function, Smarandache Notions Journal, Vol. 11, No. 1-2-3, Spring 2000.
  • Amarnath Murthy, Properties of Smarandache Star Triangle, Smarandache Notions Journal, Vol. 11, No. 1-2-3, Spring 2000.

Programs

  • Maple
    with(combinat, stirling2): for n from 1 to 15 do for k from 1 to n do printf(`%d`, stirling2(n,k)) od: printf(`,`): od:

Extensions

More terms from James Sellers, Apr 23 2001
Previous Showing 11-20 of 644 results. Next