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 1-10 of 13 results. Next

A125274 Eigensequence of triangle A078812: a(n) = Sum_{k=0..n-1} A078812(n-1,k)*a(k) for n > 0 with a(0)=1.

Original entry on oeis.org

1, 1, 3, 10, 42, 210, 1199, 7670, 54224, 418744, 3499781, 31425207, 301324035, 3069644790, 33078375153, 375634524357, 4480492554993, 55971845014528, 730438139266281, 9935106417137098, 140553930403702487
Offset: 0

Views

Author

Paul D. Hanna, Nov 26 2006

Keywords

Examples

			a(3) = 3*(1) + 4*(1) + 1*(3) = 10;
a(4) = 4*(1) + 10*(1) + 6*(3) + 1*(10) = 42;
a(5) = 5*(1) + 20*(1) + 21*(3) + 8*(10) + 1*(42) = 210.
Triangle A078812(n,k) = binomial(n+k+1, n-k) begins:
  1;
  2,  1;
  3,  4,  1;
  4, 10,  6,  1;
  5, 20, 21,  8,  1;
  6, 35, 56, 36, 10,  1; ...
where g.f. of column k = 1/(1-x)^(2*k+2).
		

Crossrefs

Programs

  • Mathematica
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n+k, n-k-1] * a[k], {k, 0, n-1}]; Array[a, 20, 0] (* Amiram Eldar, Nov 24 2018 *)
  • PARI
    a(n)=if(n==0,1,sum(k=0,n-1, a(k)*binomial(n+k, n-k-1)))

Formula

a(n) = Sum_{k=0..n-1} binomial(n+k, n-k-1)*a(k) for n > 0 with a(0)=1.
G.f. satisfies A(x) = 1 + x/(1-x)^2*A(x/(1-x)^2). [Vladimir Kruchinin, Nov 28 2011]

A351813 G.f. A(x) satisfies: A(x) = 1 + x * A(x/(1 - x)^3) / (1 - x).

Original entry on oeis.org

1, 1, 2, 7, 32, 179, 1184, 8977, 76391, 719132, 7405261, 82654011, 992533974, 12744345310, 174073918884, 2518084939316, 38429337167618, 616676966998463, 10374679318111371, 182506045254212184, 3349265281648290030, 63984975864984809787, 1270096455615572678617
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 19 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 22; A[] = 0; Do[A[x] = 1 + x A[x/(1 - x)^3]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n + 2 k - 1, n - k - 1] a[k], {k, 0, n - 1}]; Table[a[n], {n, 0, 22}]

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} binomial(n+2*k-1,n-k-1) * a(k).

A351814 G.f. A(x) satisfies A(x) = 1 + x * A(x/(1 - x)^4) / (1 - x).

Original entry on oeis.org

1, 1, 2, 8, 42, 272, 2115, 19010, 192760, 2172468, 26896081, 362184998, 5262526484, 81969555736, 1361249430071, 23989460080079, 446832403813788, 8765575657218860, 180544405959236487, 3893718987163468969, 87711985393624557487, 2059264143275898894916
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 20 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 21; A[] = 0; Do[A[x] = 1 + x A[x/(1 - x)^4]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n + 3 k - 1, n - k - 1] a[k], {k, 0, n - 1}]; Table[a[n], {n, 0, 21}]

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} binomial(n+3*k-1,n-k-1) * a(k).

A351815 G.f. A(x) satisfies A(x) = 1 + x * A(x/(1 - x)^5) / (1 - x).

Original entry on oeis.org

1, 1, 2, 9, 53, 386, 3422, 35300, 412084, 5364255, 76952267, 1203835714, 20362911276, 369906504888, 7175947738672, 147944905766929, 3227970924123268, 74264452788294013, 1795825803391367571, 45514495928632484735, 1205981001167335524448, 33331235326744168532151
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 20 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 21; A[] = 0; Do[A[x] = 1 + x A[x/(1 - x)^5]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n + 4 k - 1, n - k - 1] a[k], {k, 0, n - 1}]; Table[a[n], {n, 0, 21}]

Formula

a(0) = 1; a(n) = Sum_{k=0..n-1} binomial(n+4*k-1,n-k-1) * a(k).

A144251 Eigensequence of triangle A054142.

Original entry on oeis.org

1, 1, 2, 6, 24, 122, 758, 5606, 48378, 479532, 5390940, 68022932, 954948752, 14804391270, 251815549396, 4673137101108, 94148342547146, 2050127343000170, 48061939075355080, 1208742383083994580, 32507565146820336836, 932149980847656487522, 28423646163259392354386, 919399182232129554488328
Offset: 0

Views

Author

Gary W. Adamson, Sep 16 2008

Keywords

Comments

Eigensequence of the reversed triangle (A085478) = A125273.
Eigentriangle A144252 has row sums of A144251 shifted: (1, 2, 6, 24, 122,...) with right border = A144251.

Examples

			Triangle A054142 begins:
  1;
  1, 1;
  1, 3, 1;
  1, 5, 6, 1;
  1, 7, 15, 10, 1;
  1, 9, 28, 35, 15, 1;
  ...
a(3) = 6 = 1*1 + 3*1 + 1*2
a(4) = 24 = 1*1 + 5*1 + 6*2 + 1*6
		

Crossrefs

Programs

  • PARI
    A054142(n, k) = binomial(2*n-k, k);
    a(n) = if (n==0, 1, sum(k=0, n-1, A054142(n-1,k)*a(k))); \\ too slow
    lista(nn) = my(v=vector(nn)); v[1] = 1; for (n=2, nn, v[n] = sum(k=0, n-1, A054142(n-2,k)*v[k+1]);); v; \\ Michel Marcus, Jan 17 2025

Formula

a(n) = Sum_{k=0..n-1} A054142(n-1,k)*a(k) for n>0 with a(0)=1.

Extensions

More terms from Seiichi Manyama, May 31 2022

A144252 Eigentriangle, row sums = A144251 shifted, right border = A144251.

Original entry on oeis.org

1, 1, 1, 1, 3, 2, 1, 5, 12, 6, 1, 7, 30, 60, 24, 1, 9, 56, 210, 360, 122, 1, 11, 90, 504, 1680, 2562, 758, 1, 13, 132, 990, 5040, 15372, 21224, 5606, 1, 15, 182, 1716, 11880, 36364, 159180, 201816, 47378, 1, 17, 240, 2730, 24024, 157014, 700392, 1849980, 2177010, 479532
Offset: 0

Views

Author

Gary W. Adamson, Sep 16 2008

Keywords

Comments

Right border = A144251: (1, 1, 2, 6, 24, 122, 758,...) with row sums = the same sequence shifted. Sum of n-th row terms = rightmost term of next row.

Examples

			First few rows of the triangle =
  1;
  1, 1;
  1, 3, 2;
  1, 5, 12, 6;
  1, 7, 30, 60, 24;
  1, 9, 56, 210, 360, 122;
  1, 11, 90, 504, 1680, 2562, 758;
  1, 13, 132, 990, 5040, 15372, 21224, 5606;
  ...
The triangle is generated from A054142 and its own eigensequence, A144251.
Triangle A054142 =
  1;
  1, 1;
  1, 3, 1;
  1, 5, 6, 1;
  1, 7, 15, 10, 1;
  ...
The eigensequence of A054142 = A144251: (1, 1, 2, 6, 24, 122, 758, 5606,...);
Example: row 3 of A144252 = (1, 5, 12, 6) = termwise products of (1, 5, 6, 1) and (1, 1, 2, 6) = (1*1, 5*1, 6*2, 1*6).
		

Crossrefs

Programs

  • PARI
    A054142(n, k) = binomial(2*n-k, k);
    V144251(nn) = my(v=vector(nn)); v[1] = 1; for (n=2, nn, v[n] = sum(k=0, n-1, A054142(n-2,k)*v[k+1]);); v;
    row(n) = my(v=V144251(n+1)); vector(n+1, k, A054142(n,k-1) * v[k]); \\ Michel Marcus, Jan 18 2025

Formula

Eigentriangle by rows, T(n,k) = A054142(n,k) * A144251(k); were A144251 = the eigensequence of triangle A054142.

Extensions

More terms from Michel Marcus, Jan 18 2025

A132427 Triangle, read by rows of 2n+1 terms, where T(n,k) = T(n,k-1) + T(n-1,k-2) for n>0, 10 and T(0,0)=1.

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 3, 4, 6, 6, 6, 8, 10, 13, 17, 23, 23, 23, 29, 35, 43, 53, 66, 83, 106, 106, 106, 129, 152, 181, 216, 259, 312, 378, 461, 567, 567, 567, 673, 779, 908, 1060, 1241, 1457, 1716, 2028, 2406, 2867, 3434, 3434, 3434, 4001, 4568, 5241, 6020, 6928, 7988
Offset: 0

Views

Author

Paul D. Hanna, Aug 21 2007

Keywords

Comments

Column 0 equals (essentially) column 1 and the rightmost border.

Examples

			Triangle begins:
1;
1, 1, 2;
2, 2, 3, 4, 6;
6, 6, 8, 10, 13, 17, 23;
23, 23, 29, 35, 43, 53, 66, 83, 106;
106, 106, 129, 152, 181, 216, 259, 312, 378, 461, 567;
567, 567, 673, 779, 908, 1060, 1241, 1457, 1716, 2028, 2406, 2867, 3434; ...
		

Crossrefs

Cf. A125273; A132428 (central terms).

Programs

  • Mathematica
    t[n_, k_] := t[n, k] = t[n, k-1] + t[n-1, k-2]; t[n_, 0] := t[n, 0] = t[n-1, 2n-2]; t[n_, 1] := t[n, 0]; t[0, 0] = 1; Flatten[ Table[t[n, k], {n, 0, 7}, {k, 0, 2 n}]] (* Jean-François Alcover, Jun 18 2012 *)
  • PARI
    T(n,k)=local(A=[1]);if(2*n
    				

Formula

The g.f. of column 0 (A125273) satisfies: G(x) = 1 + x*G( x/(1-x)^2 ) / (1-x).
The central terms (A132428) are the inverse binomial transform of A125273 (offset 1).

A132428 Central terms of triangle A132427.

Original entry on oeis.org

1, 1, 3, 10, 43, 216, 1241, 7988, 56763, 440254, 3693728, 33281359, 320112326, 3270177860, 35329070470, 402128329243, 4806784533967, 60166803598106, 786622663286330, 10717555856584617, 151864784070048105
Offset: 0

Views

Author

Paul D. Hanna, Aug 21 2007

Keywords

Crossrefs

Programs

  • Maxima
    a(n):=if n=0 then 1  else sum(sum(binomial(i-1,k-1)*binomial(i,n-i),i,k,n)*a(k-1),k,1,n); /* Vladimir Kruchinin, May 02 2012 */
  • PARI
    {a(n)=local(G=1+x+x*O(x^n));for(i=0,n,G=1+x*subst(G,x,x/(1-x)^2)/(1-x)); polcoeff(subst((G-1)/x,x,x/(1+x))/(1+x),n)}
    

Formula

Binomial transform equals A125273.
a(n)=sum(k=1..n, sum(i=k..n, binomial(i-1,k-1)*binomial(i,n-i))*a(k-1)), n>0,a(0)=1. [Vladimir Kruchinin, May 02 2012]

A144250 Eigentriangle, row sums = A125275, shifted.

Original entry on oeis.org

1, 1, 1, 1, 3, 2, 1, 6, 10, 6, 1, 10, 30, 42, 23, 1, 15, 70, 168, 207, 106, 1, 21, 140, 504, 1035, 1166, 567, 1, 28, 252, 1260, 3795, 6996, 7371, 3434
Offset: 0

Views

Author

Gary W. Adamson, Sep 16 2008

Keywords

Comments

Row sums = A125273 shifted. A125273 = the eigensequence of triangle A085478.
Right border = A125273: (1, 1, 2, 6, 23, 106, 567, 3434,...). Sum of n-th row terms = rightmost term in next row.

Examples

			First few rows of the triangle =
1;
1, 1;
1, 3, 2;
1, 6, 10, 6;
1, 10, 30, 42, 23;
1, 15, 70, 168, 207, 106;
1, 21, 140, 504, 1035, 1166, 567;
...
Row 4 = (1, 10, 30, 42, 23) = termwise products of (1, 10, 15, 7, 1) and (1, 1, 2, 6, 23) = (1*1, 10*1, 15*2, 7*6, 1*23); where (1, 10, 15, 7, 1) = row 4 of triangle A085478. Q
		

Crossrefs

Formula

Triangle read by rows, T(n,k) = A085478(n,k) * A125273(k).
As infinite lower triangular matrices, A144250 = A085478 * (A125275 * 0^(n-k); where (A125275 * 0^(n-k)) = an infinite lower triangular matrix with A125275: (1, 1, 2, 6, 23, 106, 567, 3434,...) as the main diagonal and the rest zeros.

Extensions

Corrected definition: Eigentriangle, row sums = A125273, shifted. - Gary W. Adamson, Nov 05 2008

A244888 Triangle of coefficients arising in study of up-down permutations.

Original entry on oeis.org

1, -2, 1, 6, -6, 1, -23, 36, -15, 1, 106, -229, 160, -37, 1, -567, 1574, -1566, 650, -93, 1, 3434, -11706, 15248, -9310, 2572, -238, 1, -23137, 93831, -151933, 123814, -52136, 10175, -616, 1
Offset: 1

Views

Author

N. J. A. Sloane, Jul 12 2014

Keywords

Comments

See Remmel (2014) for precise definition.

Examples

			Triangle begins:
       1;
      -2,      1;
       6,     -6,       1;
     -23,     36,     -15,      1;
     106,   -229,     160,    -37,      1;
    -567,   1574,   -1566,    650,    -93,     1;
    3434, -11706,   15248,  -9310,   2572,  -238,    1;
  -23137,  93831, -151933, 123814, -52136, 10175, -616, 1;
  ...
		

Crossrefs

First two columns are A125273 and A244889.
Showing 1-10 of 13 results. Next