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 1-7 of 7 results.

A143983 Triangle T(n,k), n>=1, 1<=k<=n, read by rows, where sequence a_k of column k has a_k(0)=1, followed by (k-1)-fold 0 and a_k(n) shifts k places down under binomial transform.

Original entry on oeis.org

1, 2, 1, 5, 1, 1, 15, 2, 1, 1, 52, 5, 1, 1, 1, 203, 13, 2, 1, 1, 1, 877, 36, 6, 1, 1, 1, 1, 4140, 109, 17, 2, 1, 1, 1, 1, 21147, 359, 44, 7, 1, 1, 1, 1, 1, 115975, 1266, 112, 23, 2, 1, 1, 1, 1, 1, 678570, 4731, 304, 65, 8, 1, 1, 1, 1, 1, 1, 4213597, 18657, 918, 165, 30, 2, 1, 1, 1, 1, 1, 1
Offset: 1

Views

Author

Alois P. Heinz, Sep 06 2008

Keywords

Comments

The matrix inverse starts:
1;
-2, 1;
-3, -1, 1;
-8, -1, -1, 1;
-31, -3, 0, -1, 1;
-132, -7, -1, 0, -1, 1;
-616, -19, -4, 0, 0, -1, 1; - R. J. Mathar, Mar 22 2013

Examples

			T(5,2) = 5, because [1,3,3,1] * [1,0,1,1] = 5.
Triangle begins:
:      1;
:      2,    1;
:      5,    1,   1;
:     15,    2,   1,  1;
:     52,    5,   1,  1, 1;
:    203,   13,   2,  1, 1, 1;
:    877,   36,   6,  1, 1, 1, 1;
:   4140,  109,  17,  2, 1, 1, 1, 1;
:  21147,  359,  44,  7, 1, 1, 1, 1, 1;
: 115975, 1266, 112, 23, 2, 1, 1, 1, 1, 1;
		

Crossrefs

Columns 1-6 give: A000110, A000994, A000996, A010748, A010749, A010750.
Cf. A007318.

Programs

  • Maple
    T:= proc(n, k) option remember; `if`(n
    				
  • Mathematica
    t[n_, k_] := t[n, k] = If[n < k, If[n == 0, 1, 0], Sum[Binomial[n-k, j]*t[j, k], {j, 0, n-k}]]; Table[Table[t[n, k], {k, 1, n}], {n, 1, 13}] // Flatten (* Jean-François Alcover, Dec 18 2013, translated from Maple *)

Formula

T(n,k) = Sum_{j=0..n-k} C(n-k,j)*T(j,k) if n>=k, else T(n,k) = 1 if n=1, else T(n,k) = 0.

A346050 G.f. A(x) satisfies: A(x) = x + x^2 + x^3 * A(x/(1 - x)) / (1 - x).

Original entry on oeis.org

0, 1, 1, 0, 1, 3, 6, 11, 23, 60, 179, 553, 1716, 5415, 17801, 61956, 228391, 882309, 3530322, 14531621, 61454091, 267479778, 1200680113, 5561767211, 26553471186, 130366882251, 656668581417, 3387887246292, 17886582294921, 96603394562849, 533645344137390, 3014295344076655
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 02 2021

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 31; A[] = 0; Do[A[x] = x + x^2 + x^3 A[x/(1 - x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = 0; a[1] = a[2] = 1; a[n_] := a[n] = Sum[Binomial[n - 3, k] a[k], {k, 0, n - 3}]; Table[a[n], {n, 0, 31}]
  • SageMath
    @CachedFunction
    def a(n): # a = A346050
        if (n<3): return (0,1,1)[n]
        else: return sum(binomial(n-3,k)*a(k) for k in range(n-2))
    [a(n) for n in range(51)] # G. C. Greubel, Nov 28 2022

Formula

a(0) = 0, a(1) = a(2) = 1; a(n) = Sum_{k=0..n-3} binomial(n-3,k) * a(k).

A346051 G.f. A(x) satisfies: A(x) = 1 + x^2 + x^3 * A(x/(1 - x)) / (1 - x).

Original entry on oeis.org

1, 0, 1, 1, 1, 2, 5, 12, 28, 68, 181, 531, 1671, 5491, 18627, 65299, 237880, 903907, 3580619, 14729777, 62639952, 274442521, 1236730244, 5729809348, 27292248240, 133614280479, 671803041553, 3464970976743, 18309428363425, 99010800275743, 547462187824465, 3093329527120022
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 02 2021

Keywords

Crossrefs

Programs

  • Magma
    function a(n)
      if n lt 3 then return (1+(-1)^n)/2;
      else return (&+[Binomial(n-3,j)*a(j): j in [0..n-3]]);
      end if; return a;
    end function;
    [a(n): n in [0..35]]; // G. C. Greubel, Nov 30 2022
    
  • Mathematica
    nmax = 31; A[] = 0; Do[A[x] = 1 + x^2 + x^3 A[x/(1 - x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = 1; a[1] = 0; a[2] = 1; a[n_] := a[n] = Sum[Binomial[n - 3, k] a[k], {k, 0, n - 3}]; Table[a[n], {n, 0, 31}]
  • SageMath
    @CachedFunction
    def a(n): # a = A346051
        if (n<3): return (1, 0, 1)[n]
        else: return sum(binomial(n-3, k)*a(k) for k in range(n-2))
    [a(n) for n in range(51)] # G. C. Greubel, Nov 30 2022

Formula

a(0) = 1, a(1) = 0, a(2) = 1; a(n) = Sum_{k=0..n-3} binomial(n-3,k) * a(k).

A346052 G.f. A(x) satisfies: A(x) = 1 + x + x^3 * A(x/(1 - x)) / (1 - x).

Original entry on oeis.org

1, 1, 0, 1, 2, 3, 5, 11, 29, 80, 222, 630, 1881, 6004, 20420, 72979, 270659, 1035590, 4087205, 16675630, 70440641, 307933393, 1390117953, 6462787357, 30871458702, 151298796000, 760250325004, 3915477534861, 20662363081756, 111662169790416, 617482470676567, 3490973387652861
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 02 2021

Keywords

Crossrefs

Programs

  • Magma
    function a(n) // a = A346052
      if n lt 3 then return Floor((3-n)/2);
      else return (&+[Binomial(n-3,j)*a(j): j in [0..n-3]]);
      end if; return a;
    end function;
    [a(n): n in [0..35]]; // G. C. Greubel, Nov 30 2022
    
  • Mathematica
    nmax = 31; A[] = 0; Do[A[x] = 1 + x + x^3 A[x/(1 - x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[0] = a[1] = 1; a[2] = 0; a[n_] := a[n] = Sum[Binomial[n - 3, k] a[k], {k, 0, n - 3}]; Table[a[n], {n, 0, 31}]
  • SageMath
    @CachedFunction
    def a(n): # a = A346052
        if (n<3): return (1, 1, 0)[n]
        else: return sum(binomial(n-3, k)*a(k) for k in range(n-2))
    [a(n) for n in range(51)] # G. C. Greubel, Nov 30 2022

Formula

a(0) = a(1) = 1, a(2) = 0; a(n) = Sum_{k=0..n-3} binomial(n-3,k) * a(k).

A351342 G.f. A(x) satisfies: A(x) = 1 + x + x^2 + x^3 * A(x/(1 - 2*x)) / (1 - 2*x).

Original entry on oeis.org

1, 1, 1, 1, 3, 9, 27, 83, 271, 971, 3865, 16879, 78985, 388385, 1987201, 10561385, 58443891, 337724057, 2040085491, 12862712499, 84357800063, 573182197539, 4021203303593, 29062345301487, 216129411635057, 1653180368063361, 13003920016983361, 105158133803473329
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 08 2022

Keywords

Comments

Shifts 3 places left under 2nd-order binomial transform.

Crossrefs

Programs

  • Mathematica
    nmax = 27; A[] = 0; Do[A[x] = 1 + x + x^2 + x^3 A[x/(1 - 2 x)]/(1 - 2 x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    a[n_] := a[n] = If[n < 3, 1, Sum[Binomial[n - 3, k] 2^k a[n - k - 3], {k, 0, n - 3}]]; Table[a[n], {n, 0, 27}]

Formula

a(0) = a(1) = a(2) = 1; a(n) = Sum_{k=0..n-3} binomial(n-3,k) * 2^k * a(n-k-3).

A336971 G.f. A(x) satisfies: A(x) = 1 - x^3 * A(x/(1 - x)) / (1 - x).

Original entry on oeis.org

1, 0, 0, -1, -1, -1, 0, 4, 15, 40, 86, 134, 16, -1060, -6119, -25187, -86678, -250846, -537819, -175233, 6998009, 55632942, 310923272, 1465146781, 6011047682, 20719304348, 49356093300, -36579100806, -1549214884054, -13807417413199, -92912464763743
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 09 2020

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 30; A[] = 0; Do[A[x] = 1 - x^3 A[x/(1 - x)]/(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] a[k], {k, 0, n - 3}]; Table[a[n], {n, 0, 30}]

Formula

a(0) = 1, a(1) = a(2) = 0; a(n) = -Sum_{k=0..n-3} binomial(n-3,k) * a(k).

A088022 a(n) = floor(sum_{k>=0} k^n /(k!)^3); related to generalized Bell numbers.

Original entry on oeis.org

2, 1, 1, 2, 3, 6, 12, 28, 68, 176, 484, 1409, 4334, 14002, 47357, 167157, 614297, 2345730, 9290084, 38092233, 161436136, 706061825, 3182452003, 14764717643, 70429572474, 345075959701, 1734987079149, 8943648710357, 47228775626154
Offset: 0

Views

Author

Paul D. Hanna, Sep 19 2003

Keywords

Examples

			a(8) = 68 = floor(17*2.1297 + 12*1.2641 + 11*1.5428) = floor(68.3463).
		

Crossrefs

Formula

B(n) := sum_{k>=0} k^n/(k!)^3 = A000996(n)*B(0) + A000997(n)*B(1) + A000998(n)*B(2) where B(0)=2.129702548983..., B(1)=1.264181150389..., B(2)=1.542838638501...; observe that these shift 3 places left under binomial transform: A000996={1, 0, 0, 1, 1, 1, 2, 6, 17, 44, 112, 304, 918, ...}, A000997={0, 1, 0, 0, 1, 2, 3, 5, 12, 36, 110, 326, 963, ...}, A000998={0, 0, 1, 0, 0, 1, 3, 6, 11, 24, 69, 227, 753, ...}; here A000998 is offset with 5 leading terms: {0, 0, 1, 0, 0}.
Showing 1-7 of 7 results.