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.

A081038 3rd binomial transform of (1,2,0,0,0,0,0,0,...).

Original entry on oeis.org

1, 5, 21, 81, 297, 1053, 3645, 12393, 41553, 137781, 452709, 1476225, 4782969, 15411789, 49424013, 157837977, 502211745, 1592728677, 5036466357, 15884240049, 49977243081, 156905298045, 491636600541, 1537671920841
Offset: 0

Views

Author

Paul Barry, Mar 03 2003

Keywords

Comments

a(n) is the number of distinguished parts in all compositions of n+1 in which some (possibly all or none) of the parts have been distinguished. a(1) = 2 because we have: 2', 1'+1, 1+1', 1'+1' where we see 5's marking the distinguished parts. With offset=1, a(n) = Sum_{k=1..n} A200139(n,k)*k. - Geoffrey Critzer, Jan 12 2013
For n>=1, a(n-1) the number of ternary strings of length 2n containing the block 11..12 with n ones where no runs of length larger than n are permitted. - Marko Riedel, Mar 08 2016
Binomial transform of {A001787(n + 1)}{n >= 0}. - _Wolfdieter Lang, Oct 01 2019

Crossrefs

Programs

Formula

G.f.: (1-x)/(1-3*x)^2.
a(n) = 6*a(n-1) - 9*a(n-2), with a(0)=1, a(1)=5.
a(n) = (2*n+3)*3^(n-1).
a(n) = Sum_{k=0..n} (k+1)*2^k*binomial(n, k).
a(n) = 2*A086972(n) - 1. - Lambert Herrgesell (zero815(AT)googlemail.com), Feb 10 2008
From Amiram Eldar, May 17 2022: (Start)
Sum_{n>=0} 1/a(n) = 9*(sqrt(3)*arctanh(1/sqrt(3)) - 1).
Sum_{n>=0} (-1)^n/a(n) = 9 - 3*sqrt(3)*Pi/2. (End)
E.g.f.: exp(3*x)*(1 + 2*x). - Stefano Spezia, Jan 31 2025

A081039 4th binomial transform of (1,3,0,0,0,0,0,.....).

Original entry on oeis.org

1, 7, 40, 208, 1024, 4864, 22528, 102400, 458752, 2031616, 8912896, 38797312, 167772160, 721420288, 3087007744, 13153337344, 55834574848, 236223201280, 996432412672, 4191888080896, 17592186044416, 73667279060992
Offset: 0

Views

Author

Paul Barry, Mar 03 2003

Keywords

Crossrefs

Programs

Formula

a(n) = 8*a(n-1) -16*a(n-2) with n>1, a(0)=1, a(1)=7.
a(n) = (3*n+4)*4^(n-1).
a(n) = Sum_{k=0..n} (k+1)*3^k*binomial(n, k).
G.f.: (1-x)/(1-4*x)^2.
E.g.f.: exp(4*x)*(1 + 3*x). - Stefano Spezia, Jan 31 2025

A081041 6th binomial transform of (1,5,0,0,0,0,0,0,...).

Original entry on oeis.org

1, 11, 96, 756, 5616, 40176, 279936, 1912896, 12877056, 85660416, 564350976, 3688436736, 23944605696, 154551545856, 992612745216, 6347497291776, 40435908673536, 256721001578496, 1624959306694656, 10257555623510016
Offset: 0

Views

Author

Paul Barry, Mar 04 2003

Keywords

Crossrefs

Programs

  • Magma
    [(5*n+6)*6^(n-1): n in [0..25]]; // Vincenzo Librandi, Aug 06 2013
  • Mathematica
    CoefficientList[Series[(1 - x)/(1 - 6 x)^2, {x, 0, 30}], x] (* Vincenzo Librandi, Aug 06 2013 *)
    LinearRecurrence[{12,-36},{1,11},20] (* Harvey P. Dale, Mar 04 2019 *)

Formula

a(n) = 12*a(n-1) - 36*a(n-2) for n>1, a(0)=1, a(1)=9.
a(n) = (5*n+6)*6^(n-1).
a(n) = Sum_{k=0..n} (k+1)*5^k*binomial(n, k).
G.f.: (1-x)/(1-6*x)^2.
E.g.f.: exp(6*x)*(1 + 5*x). - Stefano Spezia, Jan 31 2025

A193726 Triangular array: the fusion of polynomial sequences P and Q given by p(n,x)=(x+2)^n and q(n,x)=(x+2)^n.

Original entry on oeis.org

1, 1, 2, 2, 9, 10, 4, 28, 65, 50, 8, 76, 270, 425, 250, 16, 192, 920, 2200, 2625, 1250, 32, 464, 2800, 9000, 16250, 15625, 6250, 64, 1088, 7920, 32000, 77500, 112500, 90625, 31250, 128, 2496, 21280, 103600, 315000, 612500, 743750, 515625, 156250
Offset: 0

Views

Author

Clark Kimberling, Aug 04 2011

Keywords

Comments

See A193722 for the definition of fusion of two sequences of polynomials or triangular arrays.
Triangle T(n,k), read by rows, given by (1,1,0,0,0,0,0,0,0,...) DELTA (2,3,0,0,0,0,0,0,0,...) where DELTA is the operator defined in A084938. - Philippe Deléham, Oct 05 2011

Examples

			First six rows:
   1;
   1,   2;
   2,   9,  10;
   4,  28,  65,   50;
   8,  76, 270,  425,  250;
  16, 192, 920, 2200, 2625, 1250;
		

Crossrefs

Programs

  • Magma
    function T(n, k) // T = A193726
      if k lt 0 or k gt n then return 0;
      elif n lt 2 then return k+1;
      else return 2*T(n-1, k) + 5*T(n-1, k-1);
      end if;
    end function;
    [T(n, k): k in [0..n], n in [0..12]]; // G. C. Greubel, Dec 02 2023
    
  • Mathematica
    (* First program *)
    z = 8; a = 1; b = 2; c = 1; d = 2;
    p[n_, x_] := (a*x + b)^n ; q[n_, x_] := (c*x + d)^n
    t[n_, k_] := Coefficient[p[n, x], x^k]; t[n_, 0] := p[n, x] /. x -> 0;
    w[n_, x_] := Sum[t[n, k]*q[n + 1 - k, x], {k, 0, n}]; w[-1, x_] := 1
    g[n_] := CoefficientList[w[n, x], {x}]
    TableForm[Table[Reverse[g[n]], {n, -1, z}]]
    Flatten[Table[Reverse[g[n]], {n, -1, z}]]  (* A193726 *)
    TableForm[Table[g[n], {n, -1, z}]]
    Flatten[Table[g[n], {n, -1, z}]]  (* A193727 *)
    (* Second program *)
    T[n_, k_]:= T[n, k]= If[k<0 || k>n, 0, If[n<2, k+1, 2*T[n-1, k] + 5*T[n -1, k-1]]];
    Table[T[n, k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Dec 02 2023 *)
  • SageMath
    def T(n, k): # T = A193726
        if (k<0 or k>n): return 0
        elif (n<2): return k+1
        else: return 2*T(n-1, k) + 5*T(n-1, k-1)
    flatten([[T(n, k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Dec 02 2023

Formula

T(n,k) = 5*T(n-1,k-1) + 2*T(n-1,k) with T(0,0)=T(1,0)=1 and T(1,1)=2. - Philippe Deléham, Oct 05 2011
G.f.: (1-x-3*x*y)/(1-2*x-5*x*y). - R. J. Mathar, Aug 11 2015
From G. C. Greubel, Dec 02 2023: (Start)
T(n, 0) = A011782(n).
T(n, n) = A020699(n).
T(n, n-1) = A081040(n-1).
Sum_{k=0..n} T(n, k) = A169634(n-1) + (4/7)*[n=0].
Sum_{k=0..n} (-1)^k * T(n, k) = (-1)^n*A133494(n) = -A141413(n+1).
Sum_{k=0..floor(n/2)} T(n-k, k) = A002532(n) + 2*A002532(n-1) + (3/5)*[n=0].
Sum_{k=0..floor(n/2)} (-1)^k * T(n-k, k) = A045873(n) - 2*A045873(n-1) + (3/5)*[n=0]. (End)

A193727 Mirror of the triangle A193726.

Original entry on oeis.org

1, 2, 1, 10, 9, 2, 50, 65, 28, 4, 250, 425, 270, 76, 8, 1250, 2625, 2200, 920, 192, 16, 6250, 15625, 16250, 9000, 2800, 464, 32, 31250, 90625, 112500, 77500, 32000, 7920, 1088, 64, 156250, 515625, 743750, 612500, 315000, 103600, 21280, 2496, 128
Offset: 0

Views

Author

Clark Kimberling, Aug 04 2011

Keywords

Comments

This triangle is obtained by reversing the rows of the triangle A193726.
Triangle T(n,k), read by rows, given by (2,3,0,0,0,0,0,0,0,...) DELTA (1,1,0,0,0,0,0,0,0,...) where DELTA is the operator defined in A084938. - Philippe Deléham, Oct 05 2011

Examples

			First six rows:
     1;
     2,    1;
    10,    9,    2;
    50,   65,   28,   4;
   250,  425,  270,  76,   8;
  1250, 2625, 2200, 920, 192; 16;
		

Crossrefs

Programs

  • Magma
    function T(n, k) // T = A193727
      if k lt 0 or k gt n then return 0;
      elif n lt 2 then return n-k+1;
      else return 5*T(n-1, k) + 2*T(n-1, k-1);
      end if;
    end function;
    [T(n, k): k in [0..n], n in [0..12]]; // G. C. Greubel, Dec 02 2023
    
  • Mathematica
    (* First program *)
    z = 8; a = 1; b = 2; c = 1; d = 2;
    p[n_, x_] := (a*x + b)^n ; q[n_, x_] := (c*x + d)^n
    t[n_, k_] := Coefficient[p[n, x], x^k]; t[n_, 0] := p[n, x] /. x -> 0;
    w[n_, x_] := Sum[t[n, k]*q[n + 1 - k, x], {k, 0, n}]; w[-1, x_] := 1
    g[n_] := CoefficientList[w[n, x], {x}]
    TableForm[Table[Reverse[g[n]], {n, -1, z}]]
    Flatten[Table[Reverse[g[n]], {n, -1, z}]]  (* A193726 *)
    TableForm[Table[g[n], {n, -1, z}]]
    Flatten[Table[g[n], {n, -1, z}]]  (* A193727 *)
    (* Second program *)
    T[n_, k_]:= T[n, k]= If[k<0 || k>n, 0, If[n<2, n-k+1, 5*T[n-1, k] + 2*T[n-1, k-1]]];
    Table[T[n, k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Dec 02 2023 *)
  • SageMath
    def T(n, k): # T = A193727
        if (k<0 or k>n): return 0
        elif (n<2): return n-k+1
        else: return 5*T(n-1, k) + 2*T(n-1, k-1)
    flatten([[T(n, k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Dec 02 2023

Formula

T(n,k) = A193726(n,n-k).
T(n,k) = 2*T(n-1,k-1) + 5*T(n-1,k) with T(0,0)=T(1,1)=1 and T(1,0)=2. - Philippe Deléham, Oct 05 2011
G.f.: (1-3*x-x*y)/(1-5*x-2*x*y). - R. J. Mathar, Aug 11 2015
From G. C. Greubel, Dec 02 2023: (Start)
T(n, 0) = A020699(n).
T(n, 1) = A081040(n-1).
T(n, n) = A011782(n).
Sum_{k=0..n} T(n, k) = A169634(n-1) + (4/7)*[n=0].
Sum_{k=0..n} (-1)^k * T(n, k) = A133494(n).
Sum_{k=0..floor(n/2)} T(n-k, k) = 2*A015535(n) + A015535(n-1) + (1/2)*[n=0].
Sum_{k=0..floor(n/2)} (-1)^k * T(n-k, k) = 2*A107839(n-1) - A107839(n-2) + (1/2)*[n=0]. (End)

A294601 Numbers with exactly one odd decimal digit.

Original entry on oeis.org

1, 3, 5, 7, 9, 10, 12, 14, 16, 18, 21, 23, 25, 27, 29, 30, 32, 34, 36, 38, 41, 43, 45, 47, 49, 50, 52, 54, 56, 58, 61, 63, 65, 67, 69, 70, 72, 74, 76, 78, 81, 83, 85, 87, 89, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 120, 122, 124, 126, 128, 140, 142, 144, 146, 148, 160, 162, 164, 166, 168, 180
Offset: 1

Views

Author

Robert Israel, Nov 03 2017

Keywords

Comments

First differs from A054684 at position 56.
Numbers n such that A196564(n) = 1. - Felix Fröhlich, Nov 03 2017
There are (1+4*d)*5^(d-1) = 5*A081040(d+1) terms with d digits. - Robert Israel, Nov 06 2017

Crossrefs

Programs

  • Maple
    Res:= NULL:
    for t from 0 to 1000 do
      if nops(select(type,convert(t,base,10),odd))=1 then Res:= Res,t fi
    od:
    Res;
  • Mathematica
    Select[Range@ 200, Count[IntegerDigits@ #, ?OddQ] == 1 &] (* _Michael De Vlieger, Nov 03 2017 *)
  • PARI
    a196564(n) = #select(x->x%2, digits(n)) \\ after Michel Marcus
    is(n) = a196564(n)==1 \\ Felix Fröhlich, Nov 03 2017

A380747 Array read by ascending antidiagonals: A(n,k) = [x^n] (1 - x)/(1 - k*x)^2.

Original entry on oeis.org

1, -1, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 8, 5, 1, 0, 1, 20, 21, 7, 1, 0, 1, 48, 81, 40, 9, 1, 0, 1, 112, 297, 208, 65, 11, 1, 0, 1, 256, 1053, 1024, 425, 96, 13, 1, 0, 1, 576, 3645, 4864, 2625, 756, 133, 15, 1, 0, 1, 1280, 12393, 22528, 15625, 5616, 1225, 176, 17, 1
Offset: 0

Views

Author

Stefano Spezia, Jan 31 2025

Keywords

Examples

			The array begins as:
   1, 1,   1,    1,     1,     1, ...
  -1, 1,   3,    5,     7,     9, ...
   0, 1,   8,   21,    40,    65, ...
   0, 1,  20,   81,   208,   425, ...
   0, 1,  48,  297,  1024,  2625, ...
   0, 1, 112, 1053,  4864, 15625, ...
   0, 1, 256, 3645, 22528, 90625, ...
   ...
		

Crossrefs

Cf. A000012 (k=1 or n=0), A000567 (n=2), A001792 (k=2), A007778, A060747 (n=1), A081038 (k=3), A081039 (k=4), A081040 (k=5), A081041 (k=6), A081042 (k=7), A081043 (k=8), A081044 (k=9), A081045 (k=10), A103532, A154955, A380748 (antidiagonal sums).

Programs

  • Mathematica
    A[0,0]:=1; A[1,0]:=-1; A[n_,k_]:=((k-1)*n+k)k^(n-1); Table[A[n-k,k],{n,0,10},{k,0,n}]//Flatten (* or *)
    A[n_,k_]:=SeriesCoefficient[(1-x)/(1-k*x)^2,{x,0,n}]; Table[A[n-k,k],{n,0,10},{k,0,n}]//Flatten (* or *)
    A[n_,k_]:=n!SeriesCoefficient[Exp[k*x](1+(k-1)*x),{x,0,n}]; Table[A[n-k,k],{n,0,10},{k,0,n}]//Flatten

Formula

A(n,k) = ((k - 1)*n + k)*k^(n-1) with A(0,0) = 1.
A(n,k) = n! * [x^n] exp(k*x)*(1 + (k - 1)*x).
A(n,0) = A154955(n+1).
A(3,n) = A103532(n-1) for n > 0.
A(n,n) = A007778(n) for n > 0.
Showing 1-7 of 7 results.