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.

A145460 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where sequence a_k of column k is the exponential transform of C(n,k).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 0, 3, 5, 1, 0, 1, 10, 15, 1, 0, 0, 3, 41, 52, 1, 0, 0, 1, 9, 196, 203, 1, 0, 0, 0, 4, 40, 1057, 877, 1, 0, 0, 0, 1, 10, 210, 6322, 4140, 1, 0, 0, 0, 0, 5, 30, 1176, 41393, 21147, 1, 0, 0, 0, 0, 1, 15, 175, 7273, 293608, 115975, 1, 0, 0, 0, 0, 0, 6, 35, 1176, 49932, 2237921, 678570
Offset: 0

Views

Author

Alois P. Heinz, Oct 10 2008

Keywords

Comments

A(n,k) is also the number of ways of placing n labeled balls into indistinguishable boxes, where in each filled box k balls are seen at the top. E.g. A(3,1)=10:
|1.| |2.| |3.| |1|2| |1|2| |1|3| |1|3| |2|3| |2|3| |1|2|3|
|23| |13| |12| |3|.| |.|3| |2|.| |.|2| |1|.| |.|1| |.|.|.|
+--+ +--+ +--+ +-+-+ +-+-+ +-+-+ +-+-+ +-+-+ +-+-+ +-+-+-+

Examples

			Square array A(n,k) begins:
   1,   1,  1,  1,  1,  1,  ...
   1,   1,  0,  0,  0,  0,  ...
   2,   3,  1,  0,  0,  0,  ...
   5,  10,  3,  1,  0,  0,  ...
  15,  41,  9,  4,  1,  0,  ...
  52, 196, 40, 10,  5,  1,  ...
		

Crossrefs

A(2n,n) gives A029651.

Programs

  • Maple
    exptr:= proc(p) local g; g:=
              proc(n) option remember; `if`(n=0, 1,
                 add(binomial(n-1, j-1) *p(j) *g(n-j), j=1..n))
            end: end:
    A:= (n,k)-> exptr(i-> binomial(i, k))(n):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    Exptr[p_] := Module[{g}, g[n_] := g[n] = If[n == 0, 1, Sum[Binomial[n-1, j-1] *p[j]*g[n-j], {j, 1, n}]]; g]; A[n_, k_] := Exptr[Function[i, Binomial[i, k]]][n]; Table[Table[A[n, d-n], {n, 0, d}], {d, 0, 12}] // Flatten (* Jean-François Alcover, Jan 15 2014, translated from Maple *)
  • Ruby
    def ncr(n, r)
      return 1 if r == 0
      (n - r + 1..n).inject(:*) / (1..r).inject(:*)
    end
    def A(k, n)
      ary = [1]
      (1..n).each{|i| ary << (0..i - 1).inject(0){|s, j| s + ncr(i - 1, j) * ncr(j + 1, k) * ary[i - 1 - j]}}
      ary
    end
    def A145460(n)
      a = []
      (0..n).each{|i| a << A(i, n - i)}
      ary = []
      (0..n).each{|i|
        (0..i).each{|j|
          ary << a[i - j][j]
        }
      }
      ary
    end
    p A145460(20) # Seiichi Manyama, Sep 28 2017

Formula

A(0,k) = 1 and A(n,k) = Sum_{i=0..n-1} binomial(n-1,i) * binomial(i+1,k) * A(n-1-i,k) for n > 0. - Seiichi Manyama, Sep 28 2017

A292973 Square array T(n,k), n>=0, k>=0, read by antidiagonals, where T(0,k) = 1 and T(n,k) = (-1)^(k+1) * k! * Sum_{i=0..n-1} (-1)^i * binomial(n-1,i) * binomial(i+1,k) * T(n-1-i,k) for n > 0.

Original entry on oeis.org

1, 1, -1, 1, 1, 2, 1, 0, -1, -5, 1, 0, 2, -2, 15, 1, 0, 0, -6, 9, -52, 1, 0, 0, 6, 24, -4, 203, 1, 0, 0, 0, -24, -140, -95, -877, 1, 0, 0, 0, 24, 60, 870, 414, 4140, 1, 0, 0, 0, 0, -120, 240, -5922, 49, -21147, 1, 0, 0, 0, 0, 120, 360, -4830, 45416, -10088, 115975
Offset: 0

Views

Author

Seiichi Manyama, Sep 27 2017

Keywords

Examples

			Square array begins:
   1,  1,  1,   1,  1, ...
  -1,  1,  0,   0,  0, ...
   2, -1,  2,   0,  0, ...
  -5, -2, -6,   6,  0, ...
  15,  9, 24, -24, 24, ...
		

Crossrefs

Columns k=0-5 give: A292935, A003725, A292907, A292908, A292969, A292970.
Rows n=0 gives A000012.
Main diagonal gives A000142.

Programs

  • Ruby
    def f(n)
      return 1 if n < 2
      (1..n).inject(:*)
    end
    def ncr(n, r)
      return 1 if r == 0
      (n - r + 1..n).inject(:*) / (1..r).inject(:*)
    end
    def A(k, n)
      ary = [1]
      (1..n).each{|i| ary << (-1) ** (k % 2 + 1) * f(k) * (0..i - 1).inject(0){|s, j| s + (-1) ** (j % 2) * ncr(i - 1, j) * ncr(j + 1, k) * ary[i - 1 - j]}}
      ary
    end
    def A292973(n)
      a = []
      (0..n).each{|i| a << A(i, n - i)}
      ary = []
      (0..n).each{|i|
        (0..i).each{|j|
          ary << a[i - j][j]
        }
      }
      ary
    end
    p A292973(20)

Formula

T(n,k) = n! * Sum_{j=0..floor(n/k)} (-j)^(n-k*j)/(j! * (n-k*j)!) for k > 0. - Seiichi Manyama, Jul 10 2022

A292910 E.g.f.: exp(1/3! * x^3 * exp(-x)).

Original entry on oeis.org

1, 0, 0, 1, -4, 10, -10, -105, 1064, -6356, 25080, -9075, -1056660, 13219206, -106106364, 548948855, 139658960, -48411569800, 761039099824, -7815284148711, 52216924707660, -9385130453790, -6650556642220260, 132749143322588331, -1713641693856894824
Offset: 0

Views

Author

Seiichi Manyama, Sep 26 2017

Keywords

Crossrefs

Column k=3 of A292948.

Programs

  • PARI
    x='x+O('x^66); Vec(serlaplace(exp(1/3!*x^3*exp(-x))))

A292935 E.g.f.: exp(exp(-x) - 1).

Original entry on oeis.org

1, -1, 2, -5, 15, -52, 203, -877, 4140, -21147, 115975, -678570, 4213597, -27644437, 190899322, -1382958545, 10480142147, -82864869804, 682076806159, -5832742205057, 51724158235372, -474869816156751, 4506715738447323, -44152005855084346
Offset: 0

Views

Author

Seiichi Manyama, Sep 27 2017

Keywords

Crossrefs

Column k=0 of A292948.
Cf. A000110.

Programs

  • PARI
    x='x+O('x^66); Vec(serlaplace(exp(exp(-x)-1)))

Formula

a(n) = (-1)^n * A000110(n).
G.f.: Sum_{k>=0} (-x)^k / Product_{j=1..k} (1 + j*x). - Ilya Gutkovskiy, Dec 14 2019

A292909 E.g.f.: exp(1/2! * x^2 * exp(-x)).

Original entry on oeis.org

1, 0, 1, -3, 9, -40, 210, -1176, 7273, -49932, 372060, -2971540, 25359411, -230364498, 2215550428, -22460391240, 239236043985, -2669869110856, 31134833803728, -378485082644400, 4786085290280275, -62838103267148790, 855122923978737876
Offset: 0

Views

Author

Seiichi Manyama, Sep 26 2017

Keywords

Crossrefs

Column k=2 of A292948.

Programs

  • PARI
    x='x+O('x^66); Vec(serlaplace(exp(1/2!*x^2*exp(-x))))

Formula

a(n) = (-1)^n * A133189(n).

A292912 E.g.f.: exp(1/4! * x^4 * exp(-x)).

Original entry on oeis.org

1, 0, 0, 0, 1, -5, 15, -35, 105, -756, 6510, -46530, 283470, -1667380, 11457446, -99776040, 969295145, -9298091180, 86154691680, -804769174536, 8052676029420, -88489327173660, 1038440150703340, -12501684521410700, 151866259113256611
Offset: 0

Views

Author

Seiichi Manyama, Sep 26 2017

Keywords

Crossrefs

Column k=4 of A292948.
Cf. A145454.

Programs

  • Mathematica
    With[{nn=30},CoefficientList[Series[Exp[x^4/4! Exp[-x]],{x,0,nn}],x] Range[ 0,nn]!] (* Harvey P. Dale, Nov 12 2021 *)
  • PARI
    x='x+O('x^66); Vec(serlaplace(exp(1/4!*x^4*exp(-x))))

Formula

a(n) = (-1)^n * A145454(n).

A292950 E.g.f.: exp(1/5! * x^5 * exp(-x)).

Original entry on oeis.org

1, 0, 0, 0, 0, 1, -6, 21, -56, 126, -126, -2310, 32472, -287001, 2016014, -11978967, 58518096, -159272932, -1367358552, 33638536548, -450849366456, 4857267575853, -44901867052350, 349150315551037, -1912043403523176, -2260563011376054
Offset: 0

Views

Author

Seiichi Manyama, Sep 27 2017

Keywords

Crossrefs

Column k=5 of A292948.

Programs

  • PARI
    x='x+O('x^66); Vec(serlaplace(exp(1/5!*x^5*exp(-x))))
Showing 1-7 of 7 results.