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.

Previous Showing 11-20 of 21 results. Next

A062193 Fourth (unsigned) column sequence of triangle A062139 (generalized a=2 Laguerre).

Original entry on oeis.org

1, 24, 420, 6720, 105840, 1693440, 27941760, 479001600, 8562153600, 159826867200, 3116623910400, 63465795993600, 1348648164864000, 29877743960064000, 689322235650048000, 16543733655601152000, 412559358036553728000, 10678006913887272960000, 286526518855975157760000
Offset: 0

Views

Author

Wolfdieter Lang, Jun 19 2001

Keywords

Crossrefs

Programs

  • Magma
    [Factorial(n+3)*binomial(n+5, 5)/Factorial(3): n in [0..30]]; // G. C. Greubel, May 11 2018
  • Mathematica
    With[{nn=20},CoefficientList[Series[(1+15*x+30*x^2+10*x^3)/(1-x)^9, {x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Mar 02 2018 *)
  • PARI
    { f=2; for (n=0, 100, f*=n + 3; write("b062193.txt", n, " ", f*binomial(n + 5, 5)/6) ) } \\ Harry J. Smith, Aug 02 2009
    
  • PARI
    my(x='x+O('x^30)); Vec(serlaplace((1+15*x+30*x^2+10*x^3)/(1-x)^9)) \\ G. C. Greubel, May 11 2018
    
  • Sage
    [binomial(n,5)*factorial (n-2)/6 for n in range(5, 21)] # Zerinvary Lajos, Jul 07 2009
    

Formula

E.g.f.: (1+15*x+30*x^2+10*x^3)/(1-x)^9.
a(n) = A062139(n+3, 3).
a(n) = (n+3)!*binomial(n+5, 5)/3!.
If we define f(n,i,x) = Sum_{k=i..n} Sum_{j=i..k} binomial(k,j)*Stirling1(n,k)*Stirling2(j,i)*x^(k-j) then a(n-3) = (-1)^(n-1)*f(n,3,-6), (n>=3). - Milan Janjic, Mar 01 2009
From Amiram Eldar, May 06 2022: (Start)
Sum_{n>=0} 1/a(n) = 75*(Ei(1) - gamma) - 30*e - 65/4, where Ei(1) = A091725, gamma = A001620, and e = A001113.
Sum_{n>=0} (-1)^n/a(n) = 315*(gamma - Ei(-1)) - 180/e - 735/4, where Ei(-1) = -A099285. (End)

A324224 Total number T(n,k) of 1's in falling diagonals with index k in all n X n permutation matrices divided by |k|!; triangle T(n,k), n>=1, 1-n<=k<=n-1, read by rows.

Original entry on oeis.org

1, 1, 2, 1, 1, 4, 6, 4, 1, 1, 6, 18, 24, 18, 6, 1, 1, 8, 36, 96, 120, 96, 36, 8, 1, 1, 10, 60, 240, 600, 720, 600, 240, 60, 10, 1, 1, 12, 90, 480, 1800, 4320, 5040, 4320, 1800, 480, 90, 12, 1, 1, 14, 126, 840, 4200, 15120, 35280, 40320, 35280, 15120, 4200, 840, 126, 14, 1
Offset: 1

Views

Author

Alois P. Heinz, Feb 18 2019

Keywords

Examples

			Triangle T(n,k) begins:
  :                                 1                              ;
  :                           1,    2,    1                        ;
  :                     1,    4,    6,    4,    1                  ;
  :               1,    6,   18,   24,   18,    6,   1             ;
  :          1,   8,   36,   96,  120,   96,   36,   8,  1         ;
  :      1, 10,  60,  240,  600,  720,  600,  240,  60, 10,  1     ;
  :  1, 12, 90, 480, 1800, 4320, 5040, 4320, 1800, 480, 90, 12, 1  ;
		

Crossrefs

Columns k=0-6 give (offsets may differ): A000142, A001563, A001286, A005990, A061206, A062199, A062148.
Row sums give A306495(n-1).
Cf. A132159 (right part of triangle), A306234, A324225.

Programs

  • Maple
    b:= proc(s, c) option remember; (n-> `if`(n=0, c,
          add(b(s minus {i}, c+x^(n-i)), i=s)))(nops(s))
        end:
    T:= n-> (p-> seq(coeff(p, x, i)/abs(i)!, i=1-n..n-1))(b({$1..n}, 0)):
    seq(T(n), n=1..8);
    # second Maple program:
    egf:= k-> (t-> x^t/t!*hypergeom([2, t], [t+1], x))(abs(k)+1):
    T:= (n, k)-> n! * coeff(series(egf(k), x, n+1), x, n):
    seq(seq(T(n, k), k=1-n..n-1), n=1..8);
    # third Maple program:
    T:= (n, k)-> (t-> `if`(t
    				
  • Mathematica
    T[n_, k_] := With[{t = Abs[k]}, If[tJean-François Alcover, Mar 25 2021, after 3rd Maple program *)

Formula

T(n,k) = T(n,-k).
T(n,k) = (n-t)*(n-1)!/t! if t < n with t = |k|, T(n,k) = 0 otherwise.
T(n,k) = 1/|k|! * A324225(n,k).
E.g.f. of column k: x^t/t! * hypergeom([2, t], [t+1], x) with t = |k|+1.
Sum_{k=1-n..n-1} T(n,k) = A306495(n-1).

A062194 Fifth column sequence of triangle A062139 (generalized a=2 Laguerre).

Original entry on oeis.org

1, 35, 840, 17640, 352800, 6985440, 139708800, 2854051200, 59935075200, 1298593296000, 29088489830400, 674324082432000, 16183777978368000, 402104637462528000, 10339833534750720000, 275039572024369152000
Offset: 0

Views

Author

Wolfdieter Lang, Jun 19 2001

Keywords

Crossrefs

Programs

  • GAP
    List([0..15],n->Factorial(n+4)*Binomial(n+6,6)/Factorial(4)); # Muniru A Asiru, Jul 01 2018
  • Magma
    [Factorial(n+4)*Binomial(n+6, 6)/Factorial(4): n in [0..20]]; // G. C. Greubel, May 12 2018
    
  • Mathematica
    Table[(n+4)!*Binomial[n+6,6]/4!, {n, 0, 20}] (* G. C. Greubel, May 12 2018 *)
  • PARI
    { f=6; for (n=0, 100, f*=n + 4; write("b062194.txt", n, " ", f*binomial(n + 6, 6)/24) ) } \\ Harry J. Smith, Aug 02 2009
    
  • Sage
    [binomial(n,6)*factorial (n-2)/factorial (4) for n in range(6, 22)] # Zerinvary Lajos, Jul 07 2009
    

Formula

E.g.f.: (1 + 24*x + 90*x^2 + 80*x^3 + 15*x^4)/(1-x)^11.
a(n) = A062139(n+4, 4).
a(n) = (n+4)!*binomial(n+6, 6)/4!.
If we define f(n,i,x) = Sum_{k=i..n} Sum_{j=i..n} binomial(k,j) * Stirling1(n,k) * Stirling2(j,i) * x^(k-j) then a(n-4) = (-1)^n*f(n,4,-7), (n >= 4). - Milan Janjic, Mar 01 2009
From Amiram Eldar, May 06 2022: (Start)
Sum_{n>=0} 1/a(n) = 336*(gamma - Ei(1)) - 96*e + 3524/5, where gamma = A001620, Ei(1) = A091725, and e = A001113.
Sum_{n>=0} (-1)^n/a(n) = 3264*(gamma - Ei(-1)) - 1920/e - 9464/5, where Ei(-1) = -A099285. (End)

A138770 Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} such that there are exactly k entries between the entries 1 and 2 (n>=2, 0<=k<=n-2).

Original entry on oeis.org

2, 4, 2, 12, 8, 4, 48, 36, 24, 12, 240, 192, 144, 96, 48, 1440, 1200, 960, 720, 480, 240, 10080, 8640, 7200, 5760, 4320, 2880, 1440, 80640, 70560, 60480, 50400, 40320, 30240, 20160, 10080, 725760, 645120, 564480, 483840, 403200, 322560, 241920, 161280, 80640
Offset: 2

Views

Author

Emeric Deutsch, Apr 06 2008

Keywords

Comments

Sum of row n = n! = A000142(n).
The expected value of k is (n-2)/3. [Geoffrey Critzer, Dec 19 2009]

Examples

			T(4,2)=4 because we have 1342, 1432, 2341 and 2431.
Triangle starts:
  2;
  4,2;
  12,8,4;
  48,36,24,12;
  240,192,144,96,48;
  ...
		

Crossrefs

Programs

  • Maple
    T:=proc(n,k) if n-2 < k then 0 else (2*n-2*k-2)*factorial(n-2) end if end proc; for n from 2 to 10 do seq(T(n, k),k=0..n-2) end do; # yields sequence in triangular form
  • Mathematica
    Table[Table[2 (n - r) (n - 2)!, {r, 1, n - 1}], {n, 1, 10}] // Grid (* Geoffrey Critzer, Dec 19 2009 *)

Formula

T(n,k) = 2*(n-k-1)*(n-2)!.
T(n,0) = 2(n-1)! = A052849(n-1).
T(n,1) = A052582(n-2).
T(n,2) = A052609(n-2).
T(n,3) = 12*A005990(n-3).
T(n,4) = 48*A061206(n-5).
T(n,n-2) = 2(n-2)! (A052849).
Sum_{k=0..n-2} k*T(n,k) = n!*(n-2)/3 = A090672(n-1).

A167568 A triangle related to the GF(z) formulas of the rows of the ED2 array A167560.

Original entry on oeis.org

1, 0, 2, 2, -2, 6, 0, 16, -16, 24, 24, -48, 144, -120, 120, 0, 432, -864, 1392, -960, 720, 720, -2160, 8208, -12816, 14448, -8400, 5040, 0, 23040, -69120, 149760, -184320, 161280, -80640, 40320, 40320, -161280, 760320, -1716480, 2684160, -2695680
Offset: 1

Views

Author

Johannes W. Meijer, Nov 10 2009

Keywords

Comments

The GF(z) formulas given below correspond to the first ten rows of the ED2 array A167560. The polynomials in their numerators lead to the triangle given above.

Examples

			Row 1: GF(z) = 1/(1-z).
Row 2: GF(z) = 2/(1-z)^2.
Row 3: GF(z) = (2*z^2 - 2*z + 6)/(1-z)^3.
Row 4: GF(z) = (0*z^3 + 16*z^2 - 16*z + 24)/(1-z)^4.
Row 5: GF(z) = (24*z^4 - 48*z^3 + 144*z^2 - 120*z + 120)/(1-z)^5.
Row 6: GF(z) = (432*z^4 - 864*z^3 + 1392*z^2 - 960*z + 720)/(1-z)^6.
Row 7: GF(z) = (720*z^6 - 2160*z^5 + 8208*z^4 - 12816*z^3 + 14448*z^2 - 8400*z + 5040)/(1-z)^7.
Row 8: GF(z) = (0*z^7 + 23040*z^6 - 69120*z^5 + 149760*z^4 - 184320*z^3 + 161280*z^2 - 80640*z + 40320)/(1-z)^8.
Row 9: GF(z) = (40320*z^8 - 161280*z^7 + 760320*z^6 - 1716480*z^5 + 2684160*z^4 - 2695680*z^3 + 1935360*z^2 - 846720*z + 362880)/(1-z)^9.
Row 10: GF(z) = (0*z^9 + 2016000*z^8 - 8064000*z^7 + 22464000*z^6 - 39168000*z^5 + 48360960*z^4 - 40849920*z^3 + 24917760*z^2 - 9676800*z + 3628800)/(1-z)^10.
		

Crossrefs

A167560 is the ED2 array.
A005359 equals the first left hand column.
A000142(n=>1) and 2*A005990 equal the first two right hand columns.
A000142(n=>1) equals the row sums.

A317527 Number of edges in the n-alternating group graph.

Original entry on oeis.org

0, 0, 3, 24, 180, 1440, 12600, 120960, 1270080, 14515200, 179625600, 2395008000, 34248614400, 523069747200, 8499883392000, 146459529216000, 2667655710720000, 51218989645824000, 1033983353475072000, 21896118073589760000, 485363950631239680000, 11240007277776076800000
Offset: 1

Views

Author

Eric W. Weisstein, Jul 30 2018

Keywords

Comments

Looks like the denominators of g.f.: (1-x)*exp(-x) + x^2*(Chi(x) - Shi(x)), for cosh and sinh integral functions. - Benedict W. J. Irwin, Jun 04 2018

Crossrefs

Programs

  • Magma
    [0] cat [Factorial(n)*(n-2)/2: n in [2..25]]; // Vincenzo Librandi, Jul 31 2018
  • Mathematica
    Join[{0}, Table[n! (n - 2)/2, {n, 2, 20}]]
    CoefficientList[Series[x^2/(2 (-1 + x)^2), {x, 0, 19}], x] Range[20]!

Formula

a(n) = n!*(n - 2)/2 for n > 1.
a(n) = 3 * A005990(n-1) for n>1. - Alois P. Heinz, Jul 30 2018
E.g.f.: x^3/(2*(x - 1)^2).

A062195 Sixth (unsigned) column sequence of triangle A062139 (generalized a=2 Laguerre).

Original entry on oeis.org

1, 48, 1512, 40320, 997920, 23950080, 570810240, 13699445760, 333923990400, 8310997094400, 211930425907200, 5548723878297600, 149353151057510400, 4135933413900288000, 117874102296158208000
Offset: 0

Views

Author

Wolfdieter Lang, Jun 19 2001

Keywords

Crossrefs

Programs

  • Magma
    [Factorial(n+5)*Binomial(n+7, 7)/Factorial(5): n in [0..20]]; // G. C. Greubel, May 12 2018
  • Mathematica
    Table[(n+5)!*Binomial[n+7, 7]/5!, {n, 0, 20}] (* G. C. Greubel, May 12 2018 *)
  • PARI
    { f=24; for (n=0, 100, f*=n + 5; write("b062195.txt", n, " ", f*binomial(n + 7, 7)/120) ) } \\ Harry J. Smith, Aug 02 2009
    

Formula

E.g.f.: N(2;5, x)/(1-x)^13 with N(2;5, x) := Sum_{k=0..5} A062196(5, k)*x^k = 1+35*x+210*x^2+350*x^3+175*x^4+21*x^5.
a(n) = A062139(n+5, 5).
a(n) = (n+5)!*binomial(n+7, 7)/5!.
If we define f(n,i,x) = Sum_{k=i..n} Sum_{j=i..k} binomial(k,j) * Stirling1(n,k) * Stirling2(j,i) * x^(k-j) then a(n-5) = (-1)^(n-1)*f(n,5,-8), (n>=5). - Milan Janjic, Mar 01 2009
From Amiram Eldar, May 06 2022: (Start)
Sum_{n>=0} 1/a(n) = 1295*(Ei(1) - gamma) + 2170*e - 22813/3, where Ei(1) = A091725, gamma = A001620, and e = A001113.
Sum_{n>=0} (-1)^n/a(n) = 36575*(gamma - Ei(-1)) - 21700/e - 63455/3, where Ei(-1) = -A099285. (End)

A193474 Table read by rows: The coefficients of the polynomials P(n, x) = Sum{k=0..n} Sum{j=0..k} (-1)^j * 2^(-k) * binomial(k, j) * (k-2*j)^n * x^(n-k).

Original entry on oeis.org

1, 1, 0, 2, 0, 0, 6, 0, 1, 0, 24, 0, 8, 0, 0, 120, 0, 60, 0, 1, 0, 720, 0, 480, 0, 32, 0, 0, 5040, 0, 4200, 0, 546, 0, 1, 0, 40320, 0, 40320, 0, 8064, 0, 128, 0, 0, 362880, 0, 423360, 0, 115920, 0, 4920, 0, 1, 0, 3628800, 0, 4838400, 0, 1693440, 0, 130560, 0, 512, 0, 0
Offset: 1

Views

Author

Peter Luschny, Aug 01 2011

Keywords

Comments

See A196776 for a row reversed form of this triangle. - Peter Bala, Oct 06 2011

Examples

			The sequence of polynomials P(n, x) begins:
[0]    1;
[1]    1;
[2]    2;
[3]    6 +      x^2;
[4]   24 +    8*x^2;
[5]  120 +   60*x^2 +     x^4;
[6]  720 +  480*x^2 +  32*x^4;
[7] 5040 + 4200*x^2 + 546*x^4 + x^6.
		

Crossrefs

Programs

  • Maple
    A193474_polynom := proc(n,x) local k, j;
    add(add((-1)^j*2^(-k)*binomial(k,j)*(k-2*j)^n*x^(n-k),j=0..k),k=0..n) end: seq(seq(coeff(A193474_polynom(n,x),x,i),i=0..n),n=0..10);
  • Mathematica
    p[n_, x_] := Sum[(-1)^j*2^(-k)*Binomial[k, j]*(k-2*j)^n*x^(n-k), {k, 0, n}, {j, 0, k}]; t[n_, k_] := Coefficient[p[n, x], x, k]; t[0, 0] = 1; Table[t[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jan 27 2014 *)

Formula

P(n, 0) = A000142(n).
P(n, 1) = A006154(n).
P(n, 2) = A191277(n).
P(n, i) = A000111(n+1), where i is the imaginary unit.
P(n, i)*2^n = A000828(n+1).
P(n, 1/2)*2^n = A000557(n).
P(n, 1/3)*3^n = A107403(n).
P(n, i/2)*2^n = A007289(n).
G(m, x) = 1/(1 - m*sinh(x)) is the generating function of m^n*P(n, 1/m).
GI(m, x) = 1/(1 - m*sin(x)) is the generating function of m^n*P(n, i/m).
[x^2] P(n+1, x) = A005990(n).

A166553 Triangle read by rows: T(n, k) = [x^k]( (n+2)!*(3*EulerE(n, x+1) - EulerE(n, x))/4 ).

Original entry on oeis.org

1, 3, 3, 0, 24, 12, -30, 0, 180, 60, 0, -720, 0, 1440, 360, 2520, 0, -12600, 0, 12600, 2520, 0, 120960, 0, -201600, 0, 120960, 20160, -771120, 0, 3810240, 0, -3175200, 0, 1270080, 181440, 0, -61689600, 0, 101606400, 0, -50803200, 0, 14515200, 1814400
Offset: 0

Views

Author

Roger L. Bagula, Dec 12 2010

Keywords

Comments

I think the rows are indexed by t = 0, 1, 2, ..., and in each row we expand the polynomial in powers of x. - N. J. A. Sloane, Dec 14 2010
Former name: Triangle read by rows: expansion of p(x,t) = exp(x*t)*(3*exp(t) - 1)/(exp(t) + 1), with coefficient of x^n scaled by multiplication by (n!*(n + 2)!/4). - G. C. Greubel, Nov 30 2024

Examples

			Triangle begins as:
        1;
        3,      3;
        0,     24,      12;
      -30,      0,     180,      60;
        0,   -720,       0,    1440,      360;
     2520,      0,  -12600,       0,    12600,   2520;
        0, 120960,       0, -201600,        0, 120960,   20160;
  -771120,      0, 3810240,       0, -3175200,      0, 1270080, 181440;
		

Crossrefs

Programs

  • Magma
    m:= 13;
    R:=PowerSeriesRing(Integers(), m+1);
    EulerE:= func< n | (2^(n+1)/(n+1))*( Evaluate(BernoulliPolynomial(n+1), 1/2) - 2^(n+1)*Evaluate(BernoulliPolynomial(n+1), 1/4) ) >;
    f:= func< n,x | (Factorial(n+2)/2)*( 3*x^n - 2*(&+[ Binomial(n,j)*(EulerE(j)/2^j)*(x - 1/2)^(n-j): j in [0..n]]) ) >;
    A166553:= func< n,k | Coefficient(R!( f(n,x) ), k) >;
    [A166553(n,k): k in [0..n], n in [0..m]]; // G. C. Greubel, Nov 30 2024
    
  • Mathematica
    (* first program *)
    p[t_]= Exp[x*t](3*Exp[t] - 1)/(Exp[t] + 1);
    With[{m=12}, Table[(n!*(n+2)!/2)*CoefficientList[SeriesCoefficient[ Series[p[t], {t,0,m+1}], n], x], {n,0,m}]]//Flatten
    (* Second program *)
    f[n_, x_]:= (n+2)!*(3*EulerE[n, x+1] - EulerE[n, x])/4;
    A166553[n_, k_]:= Coefficient[Series[f[n, x], {x,0,n}], x, k];
    Table[A166553[n,k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Nov 30 2024 *)
  • SageMath
    def f(n,x): return (factorial(n+2)/2)*( 3*x^n - 2*sum( binomial(n,j)*euler_number(j)*(x-1/2)^(n-j)/2^j for j in range(n+1)) )
    def A166553(n,k): return ( f(n,x) ).series(x,n+1).list()[k]
    print(flatten([[A166553(n,k) for k in range(n+1)] for n in range(14)])) # G. C. Greubel, Nov 30 2024

Formula

T(n, k) = [x^k]( p(n, x) ), where p(n, x) = (n!*(n+2)!/2) * [t^n]( exp(x*t)*(3*exp(t) - 1)/(exp(t) + 1) ).
From G. C. Greubel, Nov 30 2024: (Start)
T(n, k) = [x^k]( (n+2)!*(3*EulerE(n, x+1) - EulerE(n, x))/4 ).
T(n, k) = [x^k]( (1/2)*(n+2)!*( 3*x^n - 2*Sum_{j=0..n} binomial(n,j)*(EulerE(j)/2^j)*(x - 1/2)^(n-j) ) ).
T(n, n) = 3*A001715(n+2) = (n+2)!/2.
T(n, n-1) = 3*A005990(n+1). (End)

Extensions

I rewrote the definition. - N. J. A. Sloane, Dec 14 2010
New name by G. C. Greubel, Nov 30 2024

A292930 Triangle read by rows: T(n,k) (n>=1, 3<=k<=n+2) is the number of k-sequences of balls colored with at most n colors such that exactly three balls are the same color as some other ball in the sequence.

Original entry on oeis.org

1, 2, 8, 3, 24, 60, 4, 48, 240, 480, 5, 80, 600, 2400, 4200, 6, 120, 1200, 7200, 25200, 40320, 7, 168, 2100, 16800, 88200, 282240, 423360, 8, 224, 3360, 33600, 235200, 1128960, 3386880, 4838400, 9, 288, 5040, 60480, 529200, 3386880, 15240960, 43545600, 59875200, 10, 360, 7200, 100800, 1058400, 8467200, 50803200, 217728000, 598752000, 798336000
Offset: 1

Views

Author

Jeremy Dover, Sep 26 2017

Keywords

Comments

Note that the three matching balls are necessarily the same color.

Examples

			n=1 => AAA -> T(1,3)=1;
n=2 => AAA,BBB -> T(2,3)=2;
       AAAB,AABA,ABAA,BAAA,BBBA,BBAB,BABB,ABBB -> T(2,4)=8.
Triangle begins:
  1;
  2, 8;
  3, 24, 60;
  4, 48, 240, 480;
  5, 80, 600, 2400, 4200;
  ...
		

Crossrefs

Columns of table: T(n,3) = A000027(n), T(n,4) = A033996(n).
Other sequences in table: T(n,n+2) = A005990(n+1).

Programs

  • PARI
    T(n, k) = binomial(k,3)*n!/(n+2-k)!;
    tabl(nn) = for (n=1, nn, for (k=3, n+2, print1(T(n,k), ", ")); print()); \\ Michel Marcus, Sep 29 2017

Formula

T(n, k) = binomial(k,3)*n!/(n+2-k)!.
Previous Showing 11-20 of 21 results. Next