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 1-4 of 4 results.

A193657 First difference of A002627.

Original entry on oeis.org

1, 2, 7, 31, 165, 1031, 7423, 60621, 554249, 5611771, 62353011, 754471433, 9876716941, 139097096919, 2097156230471, 33704296561141, 575219994643473, 10389911153247731, 198019483156015579, 3971390745517868001, 83608226221428800021, 1843561388182505040463
Offset: 0

Views

Author

Clark Kimberling, Aug 02 2011

Keywords

Comments

Previous name was: Q-residue of the triangle A094727, where Q is the triangular array (t(i,j)) given by t(i,j)=1. For the definition of Q-residue, see A193649.
Number of n X n rook placements avoiding the pattern 001. - N. J. A. Sloane, Feb 04 2013
Let M(n) denote the n X n matrix with ones along the subdiagonal, ones everywhere above the main diagonal, the integers 2, 3, etc., along the main diagonal, and zeros everywhere else. Then a(n) is equal to the permanent of M(n). - John M. Campbell, Apr 20 2021

Crossrefs

Programs

  • Maple
    a := n -> 1-n*GAMMA(n+1)+exp(1)*n*GAMMA(n+1,1):
    seq(simplify(a(n)), n=0..9); # Peter Luschny, May 30 2014
  • Mathematica
    q[n_, k_] := n + k + 1;  (* A094727 *)
    r[0] = 1; r[k_] := Sum[q[k - 1, i] r[k - 1 - i], {i, 0, k - 1}]
    p[n_, k_] := 1
    v[n_] := Sum[p[n, k] r[n - k], {k, 0, n}]
    Table[v[n], {n, 0, 18}]    (* A193657 *)
    TableForm[Table[q[i, k], {i, 0, 4}, {k, 0, i}]]
    Table[r[k], {k, 0, 8}]  (* A193668 *)
    TableForm[Table[p[n, k], {n, 0, 4}, {k, 0, 4}]]
    CoefficientList[Series[(E^x-x)/(x-1)^2,{x,0,20}],x]*Range[0,20]! (* Vaclav Kotesovec, Nov 20 2012 *)
  • PARI
    a(n) = { sum(k=0, n, if (k <= n-2, binomial(n,k)*(k+1)!, binomial(n,k)^2*k!));} \\ Michel Marcus, Feb 07 2013
    
  • Sage
    def A193657():
        a = 2; b = 7; c = 31; n = 3
        yield 1
        while True:
            yield a
            n += 1
            a,b,c = b,c,((n-2)^2*a+2*(1+n-n^2)*b+(3*n+n^2-2)*c)/n
    a = A193657(); [next(a) for n in range(19)] # Peter Luschny, May 30 2014

Formula

E.g.f.: (exp(x)-x)/(x-1)^2. - Vaclav Kotesovec, Nov 20 2012
a(n) ~ n!*n*(e-1). - Vaclav Kotesovec, Nov 20 2012
a(n) = 1-n*Gamma(n+1)+e*n*Gamma(n+1,1). - Peter Luschny, May 30 2014
a(n) +(-n-2)*a(n-1) +(n-1)*a(n-2)=0. - R. J. Mathar, May 30 2014
From Peter Bala, Feb 10 2020: (Start)
a(n) = n*A002627(n) + 1.
a(n) = A114870(n) + n!.
a(n) = A296964(n+1) - A296964(n) for n >= 2.
a(1) = 2 and a(n) = (n^2*a(n-1) - 1)/(n - 1) for n >= 2. See A082425 for solutions to this recurrence with different starting values.
Also, a(0) = 1 and a(n) = n*( a(n-1) + ... + a(0) ) + 1 for n >= 1.
Second column of A176305. (End)

Extensions

Simpler definition by Peter Luschny, May 30 2014

A156072 T(n,k) = 1 + a(n) - a(k) - a(n - k), where a(n) = A078012(n+2), triangle read by rows (n >= 0, 0 <= k <= n).

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 3, 2, 1, 1, 1, 2, 3, 4, 4, 3, 2, 1, 1, 3, 5, 6, 6, 6, 5, 3, 1, 1, 4, 7, 9, 9, 9, 9, 7, 4, 1, 1, 6, 10, 13, 14, 14, 14, 13, 10, 6, 1, 1, 9, 15, 19, 21, 22, 22, 21, 19, 15, 9, 1, 1, 13, 22, 28, 31, 33, 34, 33, 31, 28, 22, 13, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 03 2009

Keywords

Examples

			Triangle begins:
  1;
  1, 1;
  1, 0,  1;
  1, 0,  0,  1;
  1, 1,  1,  1,  1;
  1, 1,  2,  2,  1,  1;
  1, 1,  2,  3,  2,  1,  1;
  1, 2,  3,  4,  4,  3,  2,  1;
  1, 3,  5,  6,  6,  6,  5,  3,  1;
  1, 4,  7,  9,  9,  9,  9,  7,  4, 1;
  1, 6, 10, 13, 14, 14, 14, 13, 10, 6, 1;
  ...
		

Crossrefs

Programs

  • Mathematica
    Clear[a, t, n, m];
    a[0] = 0; a[1] = 1; a[2] = 1;
    a[n_] := a[n] = a[n - 1] + a[n - 3];
    t[n_, m_] := 1 + a[n] - a[m] - a[n - m];
    Table[Table[t[n, m], {m, 0, n}], {n, 0, 10}];
    Flatten[%]
  • Maxima
    (a[0] : 0, a[1] : 1, a[2] : 1, a[n] := a[n - 1] + a[n - 3], T(n,k) := 1 + a[n] - a[k] - a[n-k])$ create_list(T(n, k), n, 0, 20, k, 0, n); /* Franck Maminirina Ramaharo, Nov 25 2018 */

Extensions

Edited and name clarified by Franck Maminirina Ramaharo, Nov 25 2018

A176344 T(n,k) = 1 + A176343(n) - A176343(k) - A176343(n-k), triangle read by rows (n >= 0, 0 <= k <= n).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 3, 3, 1, 1, 11, 13, 11, 1, 1, 65, 75, 75, 65, 1, 1, 568, 632, 640, 632, 568, 1, 1, 7789, 8356, 8418, 8418, 8356, 7789, 1, 1, 168761, 176549, 177114, 177168, 177114, 176549, 168761, 1, 1, 5847568, 6016328, 6024114, 6024671, 6024671, 6024114, 6016328, 5847568, 1
Offset: 0

Views

Author

Roger L. Bagula, Apr 15 2010

Keywords

Examples

			Triangle begins:
  1;
  1,      1;
  1,      1,      1;
  1,      3,      3,      1;
  1,     11,     13,     11,      1;
  1,     65,     75,     75,     65,      1;
  1,    568,    632,    640,    632,    568,      1;
  1,   7789,   8356,   8418,   8418,   8356,   7789,      1;
  1, 168761, 176549, 177114, 177168, 177114, 176549, 168761, 1;
  ...
		

Crossrefs

Programs

  • GAP
    b:= function(n)
        if n=0 then return 0;
        else return 1 + Fibonacci(n)*b(n-1);
        fi; end;
    T:= function(n,k) return 1 + b(n) - b(n-k) - b(k); end;
    Flat(List([0..10], n-> List([0..n], k-> T(n,k) ))); # G. C. Greubel, Dec 07 2019
  • Magma
    function b(n)
      if n eq 0 then return 0;
      else return 1 + Fibonacci(n)*b(n-1);
      end if; return b; end function;
    function T(n,k) return 1 + b(n) - b(n-k) - b(k); end function; [ T(n,k) : k in [0..n], n in [0..10]]; // G. C. Greubel, Dec 07 2019
    
  • Maple
    with(combinat);
    b:= proc(n) option remember;
       if n = 0 then 0    else 1+fibonacci(n)*b(n-1)
       fi; end proc;
    T:= proc (n, k) 1+b(n)-b(n-k)-b(k) end proc;
    seq(seq(T(n, k), k = 0..n), n = 0..10); # G. C. Greubel, Dec 08 2019
  • Mathematica
    b[n_]:= b[n]= If[n==0, 0, Fibonacci[n]*b[n-1] + 1]; (* A176343 *)
    T[n_, k_]:= T[n, k] = 1 + a[n] - a[n-k] - a[k];
    Table[T[n, k], {n,0,10}, {k,0,n}]//Flatten (* modified by G. C. Greubel, Dec 08 2019 *)
  • Maxima
    (a[0] : 0, a[n] := fib(n)*a[n-1] + 1, T(n, m) := 1 + a[n] - a[m] - a[n-m])$ create_list(T(n, m), n, 0, 10, m, 0, n); /* Franck Maminirina Ramaharo, Nov 25 2018 */
    
  • PARI
    b(n) = if(n==0, 0, 1 + fibonacci(n)*b(n-1) );
    T(n,k) = 1 + b(n) - b(n-k) - b(k);
    for(n=0,10, for(k=0,n, print1(T(n,k), ", "))) \\ G. C. Greubel, Dec 07 2019
    
  • Sage
    def b(n):
        if (n==0): return 0
        else: return 1 + fibonacci(n)*b(n-1)
    def T(n,k): return 1 + b(n) - b(n-k) - b(k)
    [[T(n,k) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Dec 07 2019
    

Extensions

Edited and name clarified by Franck Maminirina Ramaharo, Nov 25 2018

A176625 T(n,k) = 1 + 3*k*(k - n), triangle read by rows (n >= 0, 0 <= k <= n).

Original entry on oeis.org

1, 1, 1, 1, -2, 1, 1, -5, -5, 1, 1, -8, -11, -8, 1, 1, -11, -17, -17, -11, 1, 1, -14, -23, -26, -23, -14, 1, 1, -17, -29, -35, -35, -29, -17, 1, 1, -20, -35, -44, -47, -44, -35, -20, 1, 1, -23, -41, -53, -59, -59, -53, -41, -23, 1, 1, -26, -47, -62, -71, -74, -71, -62, -47
Offset: 0

Views

Author

Roger L. Bagula, Apr 22 2010

Keywords

Examples

			Triangle begins:
  1;
  1,   1;
  1,  -2,   1:
  1,  -5,  -5,   1;
  1,  -8, -11,  -8,   1;
  1, -11, -17, -17, -11,   1;
  1, -14, -23, -26, -23, -14,   1;
  1, -17, -29, -35, -35, -29, -17,   1;
  1, -20, -35, -44, -47, -44, -35, -20,   1;
  1, -23, -41, -53, -59, -59, -53, -41, -23,  1;
  1, -26, -47, -62, -71, -74, -71, -62, -47, -26, 1;
  ...
		

Crossrefs

Programs

  • Magma
    / * As triangle */ [[1 + 3*k*(k - n): k in [0..n]]: n in [0.. 15]];  // Vincenzo Librandi, Nov 26 2018
  • Mathematica
    a[n_] = n*(3*n - 1)/2; (* A000326 *)
    t[n_, m_] = 1 - a[n] + a[m] + a[n - m];
    Table[Table[t[n, m], {m, 0, n}], {n, 0, 10}];
    Flatten[%]
  • Maxima
    create_list(1 + 3*k*(k - n), n, 0, 20, k, 0, n); /* Franck Maminirina Ramaharo, Nov 25 2018 */
    

Formula

T(n,k) = 1 - A000326(n) + A000326(k) + A000326(n-k).

Extensions

Edited and name clarified by Franck Maminirina Ramaharo, Nov 25 2018
Showing 1-4 of 4 results.