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.

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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

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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

A185263 Triangle T(n,k) read by rows: coefficients (in compressed forms) in order of decreasing exponents of polynomials p_n(t) related to Hultman numbers.

Original entry on oeis.org

1, 1, 1, 1, 1, 5, 1, 15, 8, 1, 35, 84, 1, 70, 469, 180, 1, 126, 1869, 3044, 1, 210, 5985, 26060, 8064, 1, 330, 16401, 152900, 193248, 1, 495, 39963, 696905, 2286636, 604800, 1, 715, 88803, 2641925, 18128396, 19056960, 1, 1001, 183183, 8691683, 109425316, 292271616, 68428800, 1, 1365, 355355, 25537655, 539651112, 2961802480, 2699672832
Offset: 0

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Author

N. J. A. Sloane, Jan 21 2012

Keywords

Comments

Row n contains floor(n/2) + 1 terms.

Examples

			Triangle begins:
  n\k| 0    1      2       3         4         5        6
-----+---------------------------------------------------
   0 | 1
   1 | 1
   2 | 1    1
   3 | 1    5
   4 | 1   15      8
   5 | 1   35     84
   6 | 1   70    469     180
   7 | 1  126   1869    3044
   8 | 1  210   5985   26060      8064
   9 | 1  330  16401  152900    193248
  10 | 1  495  39963  696905   2286636    604800
  11 | 1  715  88803 2641925  18128396  19056960
  12 | 1 1001 183183 8691683 109425316 292271616 68428800
  ...
Polynomials p_n(t):
  p_0 = t;
  p_1 = t^2;
  p_2 = t^3 +     t;
  p_3 = t^4 +   5*t^2;
  p_4 = t^5 +  15*t^3 +    8*t;
  p_5 = t^6 +  35*t^4 +   84*t^2;
  p_6 = t^7 +  70*t^5 +  469*t^3 +  180*t;
  p_7 = t^8 + 126*t^6 + 1869*t^4 + 3044*t^2;
  ...
A(x;t) = t + t^2*x/1! + (t^3 + t)*x^2/2! + (t^4 + 5*t^2)*x^3/3! + ...
		

Crossrefs

For uncompressed form of polynomial coefficients, in order of increasing powers, see A164652.

Programs

  • Mathematica
    T[n_, k_] := Abs[StirlingS1[n+2, n-2k+1]]/Binomial[n+2, 2];
    Table[T[n, k], {n, 0, 13}, {k, 0, n/2}] // Flatten (* Jean-François Alcover, Aug 12 2018 *)
  • PARI
    seq(N) = {
      my(p=vector(N), t='t, v); p[1] = t^2; p[2] = t^3 + t;
      for (n=3, N,
        p[n] = ((2*n+1)*t*p[n-1] + (n-1)*(n^2-t^2)*p[n-2])/(n+2));
      v = vector(#p, n, vector(1+n\2, k, polcoeff(p[n], n+1-2*(k-1))));
      concat([[1]], v);
    };
    concat(seq(13))
    
  • PARI
    N=14; x='x+O('x^(N+1));
    concat(apply(p->select(a->a!=0, Vec(p)), Vec(serlaplace(((1-x)^(-t) - (1+x)^t)/x^2))))
    
  • PARI
    T(n,k) = -stirling(n+2, n+1-2*k, 1)/binomial(n+2,2);
    concat(1, concat(vector(13, n, vector(1+n\2, k, T(n, k-1)))))
    \\ Gheorghe Coserea, Jan 29 2018

Formula

From Gheorghe Coserea, Jan 29 2018: (Start)
p(n) = Sum_{k=0..floor(n/2)} T(n,k)*t^(n+1-2*k) satisfies (n+2)*p(n) = (2*n+1)*t*p(n-1) + (n-1)*(n^2-t^2)*p(n-2), n >= 2. (th. 3, (iii))
E.g.f. A(x;t) = Sum_{n>=0} p(n)*x^n/n! = ((1-x)^(-t) - (1+x)^t)/x^2. (th. 3, (i))
T(n,k) = -Stirling1(n+2, n+1-2*k)/binomial(n+2,2), where Stirling1(n,k) is defined by A048994.
A000142(n) = p(n)(1), A052572(n) = p(n)(2) for n > 0, A060593(n) = T(2*n, n) for n > 0. (End)
n-th row polynomial R(n,x) satisfies x*R(n,x^2) = (1/2)*( P(n+1,x) - P(n+1,-x) )/ binomial(n+2,2), where P(k,x) = (1 + x)*(1 + 2*x) * ... *(1 + k*x). - Peter Bala, May 14 2023

Extensions

More terms from Gheorghe Coserea, Jan 29 2018

A214178 Triangle T(n,k) by rows: the k-th derivative of the Fibonacci Polynomial F_n(x) evaluated at x=1.

Original entry on oeis.org

0, 1, 0, 1, 1, 0, 2, 2, 2, 0, 3, 5, 6, 6, 0, 5, 10, 18, 24, 24, 0, 8, 20, 44, 84, 120, 120, 0, 13, 38, 102, 240, 480, 720, 720, 0, 21, 71, 222, 630, 1560, 3240, 5040, 5040, 0, 34, 130, 466, 1536, 4560, 11760, 25200, 40320, 40320, 0, 55, 235, 948, 3564, 12264
Offset: 0

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Author

Keywords

Comments

T(n,0) = A000045(n), Fibonacci numbers;
T(n,1) = A001629(n) for n > 0;
T(n,n-3) = A038720(n-2) for n > 2;
T(n,n-2) = A000142(n-1) for n > 1;
T(n,n-1) = A000142(n-1) for n > 0;
T(n,n) = 0.

Examples

			The triangle begins:
.   0: [0]
.   1: [1, 0]
.   2: [1, 1, 0]
.   3: [2, 2, 2, 0]
.   4: [3, 5, 6, 6, 0]
.   5: [5, 10, 18, 24, 24, 0]
.   6: [8, 20, 44, 84, 120, 120, 0]
.   7: [13, 38, 102, 240, 480, 720, 720, 0]
.   8: [21, 71, 222, 630, 1560, 3240, 5040, 5040, 0]
.   9: [34, 130, 466, 1536, 4560, 11760, 25200, 40320, 40320, 0]
.  10: [55, 235, 948, 3564, 12264, 37800, 100800, 221760, 362880, 362880, 0]
       ...
		

Crossrefs

Programs

  • Haskell
    a214178 n k = a214178_tabl !! n !! k
    a214178_row n = a214178_tabl !! n
    a214178_tabl = [0] : map f a037027_tabl where
       f row = (zipWith (*) a000142_list row) ++ [0]
  • Mathematica
    T[n_, k_] := D[Fibonacci[n, x], {x, k}] /. x -> 1;
    Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Sep 20 2021 *)

Formula

T(n,k) = A037027(n,k)*k!, 0 <= k < n; T(n,n) = 0.

A230056 G.f.: Sum_{n>=0} (n+3)^n * x^n / (1 + (n+3)*x)^n.

Original entry on oeis.org

1, 4, 9, 30, 132, 720, 4680, 35280, 302400, 2903040, 30844800, 359251200, 4550515200, 62270208000, 915372057600, 14384418048000, 240612083712000, 4268249137152000, 80029671321600000, 1581386305314816000, 32844177110384640000, 715273190403932160000, 16298010552775311360000
Offset: 0

Views

Author

Paul D. Hanna, Oct 07 2013

Keywords

Examples

			O.g.f.: A(x) = 1 + 4*x + 9*x^2 + 30*x^3 + 132*x^4 + 720*x^5 + 4680*x^6 +...
where
A(x) = 1 + 4*x/(1+4*x) + 5^2*x^2/(1+5*x)^2 + 6^3*x^3/(1+6*x)^3 + 7^4*x^4/(1+7*x)^4 + 8^5*x^5/(1+8*x)^5 +...
E.g.f.: E(x) = 1 + 4*x + 9*x^2/2! + 30*x^3/3! + 132*x^4/4! + 720*x^5/5! +...
where
E(x) = 1 + 4*x + 9/2*x^2 + 5*x^3 + 11/2*x^4 + 6*x^5 + 13/2*x^6 + 7*x^7 +...
which is the expansion of: (2 + 4*x - 5*x^2) / (2 - 4*x + 2*x^2).
		

Crossrefs

Programs

  • Maple
    a:=series(add((n+3)^n*x^n/(1+(n+3)*x)^n,n=0..100),x=0,23): seq(coeff(a,x,n),n=0..22); # Paolo P. Lava, Mar 27 2019
  • Mathematica
    a[n_] := (n + 7)*n!/2; a[0] = 1; Array[a, 25, 0] (* Amiram Eldar, Dec 11 2022 *)
  • PARI
    {a(n)=polcoeff( sum(m=0, n, ((m+3)*x)^m / (1 + (m+3)*x +x*O(x^n))^m), n)}
    for(n=0, 20, print1(a(n), ", "))
    
  • PARI
    {a(n)=if(n==0, 1, (n+7) * n!/2 )}
    for(n=0, 20, print1(a(n), ", "))

Formula

a(n) = (n+7) * n!/2 for n>0 with a(0)=1.
E.g.f.: (2 + 4*x - 5*x^2)/(2*(1-x)^2).
From Amiram Eldar, Dec 11 2022: (Start)
Sum_{n>=0} 1/a(n) = 530*e - 10075/7.
Sum_{n>=0} (-1)^n/a(n) = 10085/7 - 3914/e. (End)
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