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 1-5 of 5 results.

A117937 Triangle, rows = inverse binomial transforms of A117938 columns.

Original entry on oeis.org

1, 1, 1, 3, 3, 2, 4, 10, 12, 6, 7, 27, 58, 60, 24, 11, 71, 240, 420, 360, 120, 18, 180, 920, 2460, 3504, 2520, 720, 29, 449, 3360, 13020, 27720, 32760, 20160, 5040, 47, 1107, 11898, 64620, 194184, 337680, 338400, 181440, 40320, 76, 2710, 41268, 307194, 1257120, 3029760, 4415040
Offset: 1

Views

Author

Gary W. Adamson, Apr 04 2006

Keywords

Comments

A117936 is the companion triangle using analogous Fibonacci polynomials. Left border of A117936 = the Lucas numbers; right border = factorials.
[Note that most of the comments here and in many related sequences by the same author refer to some unusual definition of binomial transforms for sequences starting at index 1. - R. J. Mathar, Jul 05 2012]

Examples

			First few rows of the triangle are:
1;
1, 1;
3, 3, 2;
4, 10, 12, 6;
7, 27, 58, 60, 24;
11, 71, 240, 420, 360, 120;
...
For example, row 4: (4, 10, 12, 6) = the inverse binomial transform of column 4 of A117938: (4, 14, 36, 76, 140...), being f(x), x =1,2,3...using the Lucas polynomial x^3 + 3x.
		

Crossrefs

Programs

  • Maple
    A117937 := proc(n,k)
        add( A117938(n+i,n)*binomial(k-1,i)*(-1)^(1+i-k),i=0..k-1) ;
    end proc:
    seq(seq(A117937(n,k),k=1..n),n=1..13) ; # R. J. Mathar, Aug 16 2019

Formula

Rows of the triangle are inverse binomial transforms of A117938 columns. A117938 columns are generated from f(x), Lucas polynomials: (1); (x); (x^2 + 2); (x^3 + 3x); (x^4 + 4x + 2);...

A309220 Square array A read by antidiagonals: the columns are given by A(n,1)=1, A(n,2)=n+1, A(n,3) = n^2+2n+3, A(n,4) = n^3+3*n^2+6*n+4, A(n,5) = n^4+4*n^3+10*n^2+12*n+7, ..., whose coefficients are given by A104509 (see also A118981).

Original entry on oeis.org

1, 1, 2, 1, 3, 6, 1, 4, 11, 14, 1, 5, 18, 36, 34, 1, 6, 27, 76, 119, 82, 1, 7, 38, 140, 322, 393, 198, 1, 8, 51, 234, 727, 1364, 1298, 478, 1, 9, 66, 364, 1442, 3775, 5778, 4287, 1154, 1, 10, 83, 536, 2599, 8886, 19602, 24476, 14159, 2786, 1, 11, 102, 756, 4354, 18557
Offset: 1

Views

Author

N. J. A. Sloane, Aug 12 2019, based on R. J. Mathar's 2011 analysis of A118980

Keywords

Comments

As pointed out by Peter Munn, A117938 gives the same triangle, except that it has an additional diagonal at the right. - N. J. A. Sloane, Aug 13 2019

Examples

			The first few antidiagonals are:
1,
1,2,
1,3,6,
1,4,11,14,
1,5,18,36,34,
1,6,27,76,119,82,
1,7,38,140,322,393,198,
...
The first nine rows of A are
1, 2, 6, 14, 34, 82, 198, 478, 1154, 2786, 6726, 16238, ...
1, 3, 11, 36, 119, 393, 1298, 4287, 14159, 46764, 154451, 510117, ...
1, 4, 18, 76, 322, 1364, 5778, 24476, 103682, 439204, 1860498, 7881196, ...
1, 5, 27, 140, 727, 3775, 19602, 101785, 528527, 2744420, 14250627, 73997555, ...
1, 6, 38, 234, 1442, 8886, 54758, 337434, 2079362, 12813606, 78960998, 486579594, ...
1, 7, 51, 364, 2599, 18557, 132498, 946043, 6754799, 48229636, 344362251, 2458765393, ...
1, 8, 66, 536, 4354, 35368, 287298, 2333752, 18957314, 153992264, 1250895426, 10161155672, ...
1, 9, 83, 756, 6887, 62739, 571538, 5206581, 47430767, 432083484, 3936182123, 35857722591, ...
1, 10, 102, 1030, 10402, 105050, 1060902, 10714070, 108201602, 1092730090, 11035502502, 111447755110, ...
		

Crossrefs

Cf. A104509, A117938, A118980, A118981, A099425 (top row), A006497 (essentially the 2nd row), A014448 (essentially the 3rd row), A087130 (essentially the 4th row).

Programs

  • Maple
    M := 12;
    A:=Array(1..2*M,1..2*M,0):
    for i from 1 to M do A[i,1]:=1; od:
    S := series((1 + x^2)/(1-x-x^2 + x*y), x, 120): # this is g.f. for A104509
    for n from 1 to M do
    R2 := expand(coeff(S, x, n));
    R3 := [seq(abs(coeff(R2,y,n-i)),i=0..n)];
    f := k-> add( R3[i]*k^(n-i+1), i=1..nops(R3) ): # this is the formula for the (n+1)-st column
    s1 := [seq(f(i),i=1..M)];
    for i from 1 to M do A[i,n+1]:=s1[i]; od:
    od:
    for i from 1 to M do lprint([seq(A[i,j],j=1..M)]); od:
    # alternative by R. J. Mathar, Aug 13 2019 :
    A104509 := proc(n,k)
        (1+x^2)/(1-x-x^2+x*y) ;
        coeftayl(%,x=0,n) ;
        coeftayl(%,y=0,k) ;
    end proc:
    A309220 := proc(n::integer,k::integer)
        local x;
        add( abs(A104509(k-1,i))*x^i,i=0..k-1) ;
        subs(x=n,%) ;
    end proc:
    seq( seq(A309220(d-k,k),k=1..d-1),d=2..13) ;

A117936 Triangle, rows = inverse binomial transforms of A073133 columns.

Original entry on oeis.org

1, 1, 1, 2, 3, 2, 3, 9, 12, 6, 5, 24, 56, 60, 24, 8, 62, 228, 414, 360, 120, 13, 156, 864, 2400, 3480, 2520, 720, 21, 387, 3132, 12606, 27360, 32640, 20160, 5040, 34, 951, 11034, 62220, 190704, 335160, 337680, 181440, 40320, 55, 2323, 38136, 294588, 1229760, 2997120, 4394880, 3820320, 1814400, 362880
Offset: 1

Views

Author

Gary W. Adamson, Apr 03 2006

Keywords

Comments

Left border of the triangle = Fibonacci numbers, right border = factorials. Companion triangle A117937 is generated from Lucas polynomials, using analogous operations.
Note that binomial transforms are defined from offset 1 here. - R. J. Mathar, Aug 16 2019

Examples

			First few columns of A073133 are: (1, 1, 1, ...); (1, 2, 3, ...); (2, 5, 10, 17, ...); (3, 12, 33, 72, ...). As sequences, these are f(x), Fibonacci polynomials: (1); (x); (x^2 + 1); (x^3 + 2*x); (x^4 + 3*x^2 + 1); (x^5 + 4*x^3 + 3*x); ... For example, f(x), x = 1,2,3,... using (x^4 + 3*x^2 + 1) generates Column 5 of A073133: (5, 29, 109, 305, ...).
Inverse binomial transforms of the foregoing columns generates the triangle rows:
  1;
  1,  1;
  2,  3,   2;
  3,  9,  12,   6;
  5, 24,  56,  60,  24;
  8, 62, 228, 414, 360, 120;
  ...
		

Crossrefs

Cf. A006684 (column 2), A309717 (column 3 halved).

Programs

  • Maple
    A117936 := proc(n,k)
        add( A073133(i+1,n)*binomial(k-1,i)*(-1)^(i-k-1),i=0..k-1) ;
    end proc:
    seq(seq(A117936(n,k),k=1..n),n=1..13) ; # R. J. Mathar, Aug 16 2019
  • Mathematica
    (* A = A073133 *) A[, 1] = 1; A[n, k_] := A[n, k] = If[k < 0, 0, n A[n, k - 1] + A[n, k - 2]];
    T[n_, k_] := Sum[A[i+1, n] Binomial[k-1, i] (-1)^(i - k - 1), {i, 0, k-1}];
    Table[T[n, k], {n, 1, 10}, {k, 1, n}] // Flatten (* Jean-François Alcover, Apr 01 2020, from Maple *)
  • Sage
    @CachedFunction
    def A073133(n,k): return 0 if (k<0) else 1 if (k==1) else n*A073133(n,k-1) + A073133(n,k-2)
    def A117936(n,k): return sum( (-1)^(j-k+1)*binomial(k-1, j)*A073133(j+1,n) for j in (0..k-1) )
    flatten([[A117936(n,k) for k in (1..n)] for n in (1..12)]) # G. C. Greubel, Oct 23 2021

Formula

Inverse binomial transforms of A073133 columns. Such columns are f(x), Fibonacci polynomials.

A352362 Array read by ascending antidiagonals. T(n, k) = L(k, n) where L are the Lucas polynomials.

Original entry on oeis.org

2, 2, 0, 2, 1, 2, 2, 2, 3, 0, 2, 3, 6, 4, 2, 2, 4, 11, 14, 7, 0, 2, 5, 18, 36, 34, 11, 2, 2, 6, 27, 76, 119, 82, 18, 0, 2, 7, 38, 140, 322, 393, 198, 29, 2, 2, 8, 51, 234, 727, 1364, 1298, 478, 47, 0, 2, 9, 66, 364, 1442, 3775, 5778, 4287, 1154, 76, 2
Offset: 0

Views

Author

Peter Luschny, Mar 18 2022

Keywords

Examples

			Array starts:
n\k 0, 1,  2,   3,    4,     5,      6,       7,        8, ...
--------------------------------------------------------------
[0] 2, 0,  2,   0,    2,     0,      2,       0,        2, ... A010673
[1] 2, 1,  3,   4,    7,    11,     18,      29,       47, ... A000032
[2] 2, 2,  6,  14,   34,    82,    198,     478,     1154, ... A002203
[3] 2, 3, 11,  36,  119,   393,   1298,    4287,    14159, ... A006497
[4] 2, 4, 18,  76,  322,  1364,   5778,   24476,   103682, ... A014448
[5] 2, 5, 27, 140,  727,  3775,  19602,  101785,   528527, ... A087130
[6] 2, 6, 38, 234, 1442,  8886,  54758,  337434,  2079362, ... A085447
[7] 2, 7, 51, 364, 2599, 18557, 132498,  946043,  6754799, ... A086902
[8] 2, 8, 66, 536, 4354, 35368, 287298, 2333752, 18957314, ... A086594
[9] 2, 9, 83, 756, 6887, 62739, 571538, 5206581, 47430767, ... A087798
A007395|A059100|
    A001477 A079908
		

Crossrefs

Cf. A320570 (main diagonal), A114525, A309220 (variant), A117938 (variant), A352361 (Fibonacci polynomials), A350470 (Jacobsthal polynomials).

Programs

  • Maple
    T := (n, k) -> (n/2 + sqrt((n/2)^2 + 1))^k + (n/2 - sqrt((n/2)^2 + 1))^k:
    seq(seq(simplify(T(n - k, k)), k = 0..n), n = 0..10);
  • Mathematica
    Table[LucasL[k, n], {n, 0, 9}, {k, 0, 9}] // TableForm
    (* or *)
    T[ 0, k_] := 2 Mod[k+1, 2]; T[n_, 0] := 2;
    T[n_, k_] := n^k Hypergeometric2F1[1/2 - k/2, -k/2, 1 - k, -4/n^2];
    Table[T[n, k], {n, 0, 9}, {k, 0, 8}] // TableForm
  • PARI
    T(n, k) = ([0, 1; 1, k]^n*[2; k])[1, 1] ;
    export(T)
    for(k = 0, 9, print(parvector(10, n, T(n - 1, k))))

Formula

T(n, k) = Sum_{j=0..floor(k/2)} binomial(k-j, j)*(k/(k-j))*n^(k-2*j) for k >= 1.
T(n, k) = (n/2 + sqrt((n/2)^2 + 1))^k + (n/2 - sqrt((n/2)^2 + 1))^k.
T(n, k) = [x^k] ((2 - n*x)/(1 - n*x - x^2)).
T(n, k) = n^k*hypergeom([1/2 - k/2, -k/2], [1 - k], -4/n^2) for n,k >= 1.

A118980 Triangle read by rows: rows = inverse binomial transforms of columns of A309220.

Original entry on oeis.org

1, 2, 1, 6, 5, 2, 14, 22, 18, 6, 34, 85, 118, 84, 24, 82, 311, 660, 780, 480, 120, 198, 1100, 3380, 5964, 6024, 3240, 720, 478, 3809, 16380, 40740, 60480, 52920, 25200, 5040, 1154, 13005, 76518, 258804, 531864, 676080, 519840, 221760, 40320, 2786, 43978, 348462, 1564314, 4286880, 7444800, 8240400
Offset: 1

Views

Author

Gary W. Adamson, May 07 2006

Keywords

Comments

First few columns of A309220:
1, 2, 6, 14, 34, ...
1, 3, 11, 36, 119, ...
1, 4, 18, 76, 322, ...
1, 5, 27, 140, 727, ...
1, 6, 38, 234, 1442, ...
1, 7, 51, 364, 2599, ...
1, 8, 66, 536, 4354, ...
...

Examples

			First few rows of the triangle:
   1;
   2,   1;
   6,   5,   2;
  14,  22,  18,   6;
  34,  85, 118,  84,  24;
  82, 311, 660, 780, 480, 120;
  ...
Column 3 of A309220 = (6, 11, 18, 27, 38, 51, ...), whose inverse binomial transform is (6, 5, 2).
		

Crossrefs

The leading column is A099425, and the rightmost two diagonals are A038720 and A000142.

Programs

  • Maple
    with(transforms);
    M := 12;
    T := [1];
    S := series((1 + x^2)/(1-x-x^2 + x*y), x, 120):
    for n from 1 to M do
    R2 := expand(coeff(S, x, n));
    R3 := [seq(abs(coeff(R2,y,n-i)),i=0..n)];
    f := k-> add( R3[i]*k^(n-i+1), i=1..nops(R3) ):
    s1 := [seq(f(i),i=1..3*n)];
    s2 := BINOMIALi(s1);
    s3 := [seq(s2[i],i=1..n+1)];
    T := [op(T), op(s3)];
    od:
    T;  # N. J. A. Sloane, Aug 12 2019

Extensions

Edited and extended by N. J. A. Sloane, Aug 12 2019, guided by the comments of R. J. Mathar from Oct 30 2011
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