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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A177700 The n-th derivative of log(1+x)*tanh(x) evaluated at x = 0.

Original entry on oeis.org

0, 0, 2, -3, 0, -10, 160, -756, 2688, -27504, 341248, -3113440, 29004800, -365574144, 5120567296, -69912541440, 1009388355584, -16301637449728, 281310403362816, -5030932957138944, 94747161802047488, -1897026741117419520
Offset: 0

Views

Author

Michel Lagneau, May 11 2010

Keywords

Examples

			The second derivative is -(tanh(x)/(x+1)^2) + 2*((1 - tanh(x)^2)/(x+1)) - 2*log(x+1)tanh(x)(1 - tanh(x)^2). At x = 0 this sets a(2) = 0 + 2 - 0 = 2.
		

Crossrefs

Cf. A177699, A133942 (derivatives of log(1+x)), A155585 (derivatives of tanh(x)).

Programs

  • Maple
    n0:= 35: T:=array(1..n0): f:=x-> ln(1+x)*tanh(x):
    for n from 1 to n0 do: T[n]:=D(f)(0):f:=D(f):od: print(T):

Extensions

a(0) inserted and keyword:sign added by R. J. Mathar, May 14 2010

A305786 Inverse Euler transform of (-1)^n * n!.

Original entry on oeis.org

-1, 2, -4, 17, -92, 576, -4156, 34159, -314368, 3199936, -35703996, 433421495, -5687955724, 80256879068, -1211781887796, 19496946534720, -333041104402860, 6019770247224496, -114794574818830716, 2303332661416242633, -48509766592884311132, 1069983257387168051076
Offset: 1

Views

Author

Seiichi Manyama, Jun 10 2018

Keywords

Examples

			(1-x) * (1-x^2)^(-2) * (1-x^3)^4 * (1-x^4)^(-17) * ... = 1 - x + 2*x^2 - 6*x^3 + 24*x^4 - ... .
		

Crossrefs

Formula

Product_{k>=1} 1/(1-x^k)^{a(k)} = Sum_{n>=0} (-1)^n * n! * x^n.
a(n) ~ (-1)^n * n!. - Vaclav Kotesovec, Oct 09 2019

A321398 a(n) = (-1)^(n+1)*n!* [x^n](log(x + 1)/2 + log(3*x + 1)/6).

Original entry on oeis.org

0, 1, 2, 10, 84, 984, 14640, 262800, 5513760, 132289920, 3571464960, 107140320000, 3535590643200, 127280784153600, 4963944354969600, 208485575730432000, 9381849600195072000, 450328759886573568000, 22966766398527823872000, 1240205379118128783360000
Offset: 0

Views

Author

Peter Luschny, Nov 10 2018

Keywords

Crossrefs

Cf. A133942 (n=1), A000165 (n=2), this sequence (n=3), A320962 (limit).

Programs

  • Magma
    m:=30; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( -Log((1-x)^3*(1-3*x))/6 )); [0] cat [Factorial(n-0)*b[n]: n in [1..(m-1)]]; // G. C. Greubel, Nov 11 2018
  • Maple
    ser := series(ln(x+1)/2 + ln(1+3*x)/6, x, 21):
    seq((-1)^(n+1)*n!*coeff(ser, x, n), n=0..19);
  • Mathematica
    CoefficientList[Series[Log[x+1]/2 + Log[1+3*x]/6, {x, 0, 50}], x]* Table[(-1)^(n+1)*n!, {n, 0, 50}] (* Stefano Spezia, Nov 10 2018 *)
  • PARI
    seq(n)={Vec(serlaplace(-log(1 - x + O(x^n))/2 - log(1 - 3*x + O(x^n))/6), -n)} \\ Andrew Howroyd, Nov 10 2018
    

Formula

E.g.f.: -log(1 - x)/2 - log(1 - 3*x)/6. - Andrew Howroyd, Nov 10 2018
3*n*(n+1)*a(n)-4*(n+1)*a(n)+a(n+2)=0. - Robert Israel, Nov 10 2018

A331725 E.g.f.: exp(x/(1 - x)) / (1 + x).

Original entry on oeis.org

1, 0, 3, 4, 57, 216, 2755, 18348, 247569, 2368432, 35256771, 436248660, 7235178313, 108919083144, 2010150360387, 35421547781116, 723689454172065, 14543895730321248, 326843345169621379, 7354350135365751972, 180610925178770615001, 4488323611011676811320
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 25 2020

Keywords

Crossrefs

Programs

  • Maple
    A331725 := proc(n)
        add((-1)^k*binomial(n,k)*k!*A000262(n-k),k=0..n) ;
    end proc:
    seq(A331725(n),n=0..42) ; # R. J. Mathar, Aug 20 2021
  • Mathematica
    nmax = 21; CoefficientList[Series[Exp[x/(1 - x)]/(1 + x), {x, 0, nmax}], x] Range[0, nmax]!
    A000262[n_] := If[n == 0, 1, n! Sum[Binomial[n - 1, k]/(k + 1)!, {k, 0, n - 1}]]; a[n_] := Sum[(-1)^k Binomial[n, k] k! A000262[n - k], {k, 0, n}]; Table[a[n], {n, 0, 21}]
    a[n_] := (-1)^n n! (1 - Sum[(-1)^j*LaguerreL[j, 1, -1]/(j+1), {j,0,n-1}]);
    Table[a[n], {n, 0, 21}] (* Peter Luschny, Feb 20 2022 *)
  • PARI
    seq(n)={Vec(serlaplace(exp(x/(1 - x) + O(x*x^n)) / (1 + x)))} \\ Andrew Howroyd, Jan 25 2020
    
  • SageMath
    def gen_a():
        F, L, S, N = 1, 1, 1, 1
        while True:
            yield F * S
            L = gen_laguerre(N - 1, 1, -1) / N
            S += L if F < 0 else -L
            F *= -N; N += 1
    a = gen_a(); print([next(a) for  in range(21)]) # _Peter Luschny, Feb 20 2022

Formula

a(n) = Sum_{k=0..n} (-1)^k * binomial(n,k) * k! * A000262(n-k).
a(n) ~ n^(n - 1/4) / (2^(3/2) * exp(1/2 - 2*sqrt(n) + n)). - Vaclav Kotesovec, Jan 26 2020
D-finite with recurrence a(n) +(-n+1)*a(n-1) -(n-1)*(n+1)*a(n-2) +(n-1)*(n-2)^2*a(n-3)=0. - R. J. Mathar, Aug 20 2021
a(n) = Sum_{k=0..n} (-1)^k * A206703(n,k). - Alois P. Heinz, Feb 19 2022
a(n) = (-1)^n*n!*(1 - Sum_{j=0..n-1}((-1)^j*LaguerreL(j, 1, -1)/(j + 1))). - Peter Luschny, Feb 20 2022

A265313 Square array read by ascending antidiagonals, complementary Bell numbers iterated by the Bell transform.

Original entry on oeis.org

1, 1, 1, 1, -1, 1, 1, -1, 0, 1, 1, -1, 2, 1, 1, 1, -1, 2, -4, 1, 1, 1, -1, 2, -6, 9, -2, 1, 1, -1, 2, -6, 22, -22, -9, 1, 1, -1, 2, -6, 24, -95, 54, -9, 1, 1, -1, 2, -6, 24, -118, 472, -139, 50, 1, 1, -1, 2, -6, 24, -120, 683, -2638, 372, 267, 1, 1, -1, 2, -6, 24
Offset: 0

Views

Author

Peter Luschny, Dec 06 2015

Keywords

Examples

			[ 1,  1, 1,  1,  1,   1,    1,     1,     1, ...] A000012
[ 1, -1, 0,  1,  1,  -2,   -9,    -9,    50, ...] A000587
[ 1, -1, 2, -4,  9, -22,   54,  -139,   372, ...] A265023
[ 1, -1, 2, -6, 22, -95,  472, -2638, 16343, ...]
[ 1, -1, 2, -6, 24, -118, 683, -4533, 33862, ...]
[ 1, -1, 2, -6, 24, -120, 718, -4989, 39405, ...]
[...                                         ...]
[ 1, -1, 2, -6, 24, -120, 720, -5040, 40320, ...] A133942
		

Crossrefs

Programs

  • Sage
    # uses[bell_transform from A264428]
    def complementary_bell_number_matrix(ord, len):
        b = [1]*len; L = [b]
        for k in (1..ord-1):
            b = [sum((-1)^n*c for (n, c) in enumerate(bell_transform(n, b))) for n in range(len)]
            L.append(b)
        return matrix(ZZ, L)
    print(complementary_bell_number_matrix(6,9))

A302190 Hurwitz logarithm of natural numbers 1,2,3,4,5,...

Original entry on oeis.org

0, 2, -1, 2, -6, 24, -120, 720, -5040, 40320, -362880, 3628800, -39916800, 479001600, -6227020800, 87178291200, -1307674368000, 20922789888000, -355687428096000, 6402373705728000, -121645100408832000, 2432902008176640000, -51090942171709440000
Offset: 0

Views

Author

N. J. A. Sloane and William F. Keigher, Apr 12 2018

Keywords

Comments

In the ring of Hurwitz sequences all members have offset 0.

Crossrefs

Cf. A133942.

Programs

  • Maple
    # first load Maple commands for Hurwitz operations from link
    s:=[seq(n,n=1..64)];
    Hlog(s);
  • Sage
    A = PowerSeriesRing(QQ, 'x')
    f = A(list(range(1,30))).ogf_to_egf().log()
    print(list(f.egf_to_ogf()))
    # F. Chapoton, Apr 11 2020

Formula

E.g.f. is log of Sum_{n >= 0} (n+1)*x^n/n!.

A355007 Triangle read by rows. T(n, k) = n^k * |Stirling1(n, k)|.

Original entry on oeis.org

1, 0, 1, 0, 2, 4, 0, 6, 27, 27, 0, 24, 176, 384, 256, 0, 120, 1250, 4375, 6250, 3125, 0, 720, 9864, 48600, 110160, 116640, 46656, 0, 5040, 86436, 557032, 1764735, 2941225, 2470629, 823543, 0, 40320, 836352, 6723584, 27725824, 64225280, 84410368, 58720256, 16777216
Offset: 0

Views

Author

Peter Luschny, Jun 17 2022

Keywords

Examples

			Table T(n, k) begins:
[0] 1;
[1] 0,    1;
[2] 0,    2,     4;
[3] 0,    6,    27,     27;
[4] 0,   24,   176,    384,     256;
[5] 0,  120,  1250,   4375,    6250,    3125;
[6] 0,  720,  9864,  48600,  110160,  116640,   46656;
[7] 0, 5040, 86436, 557032, 1764735, 2941225, 2470629, 823543;
		

Crossrefs

A000142 (column 1), A000407 (row sums), A000312 (main diagonal), A355006.
Cf. A133942.

Programs

  • Maple
    seq(seq(n^k*abs(Stirling1(n, k)), k = 0..n), n = 0..9);
  • Mathematica
    T[n_, k_] := If[n == k == 0, 1, n^k * Abs[StirlingS1[n, k]]]; Table[T[n, k], {n, 0, 8}, {k, 0, n}] // Flatten (* Amiram Eldar, Jun 17 2022 *)

Formula

Sum_{k=0..n} (-1)^k * T(n,k) = A133942(n). - Alois P. Heinz, Mar 30 2023
Conjecture: T(n,k) = A056856(n,k)*n. - R. J. Mathar, Mar 31 2023

A138160 A triangular sequence of coefficients of the expansion of a Green's function for the radial Morse potential with x being the kinetic energy and t being the radius: Hamiltonian; H=K+V=x+Exp[-2*t]-2*Exp[t];G*Exp[t*x)=Exp[x*t]/(t-H); p(t,x)=Exp[t*x]/(t-x-Exp[-2*t] + 2*Exp[-t]).

Original entry on oeis.org

1, -1, 1, -1, 4, -4, 3, -2, 1, -24, 36, -27, 13, -6, 3, -1, 182, -354, 330, -198, 85, -28, 10, -4, 1, -1730, 4090, -4480, 3120, -1595, 631, -195, 50, -15, 5, -1, 19802, -55270, 70430, -55730, 31630, -14018, 5101, -1536, 375, -80, 21, -6, 1, -264334, 850990, -1246504, 1121960, -711480, 345268, -135639, 44997, -12922, 3171, -644, 119, -28, 7, -1
Offset: 1

Views

Author

Roger L. Bagula, May 04 2008

Keywords

Comments

The row sums are:A133942; (-1)^n*n!;
{1, -1, 2, -6, 24, -120, 720, -5040, 40320, -362880, 3628800};
Plotting the relative Kinetic curves gives even peaks and odd Serpentine curves:
s = Table[Plot[g[[n]]/(1 - x)^(n + 1), {x, 0, 10}], {n, 1, Length[g]}].
It appears this method solves the spectrum of relative excited states for a Morse potential Hamiltonian system.

Examples

			Triangle begins:
  {1},
  {-1, 1, -1},
  {4, -4, 3, -2, 1},
  {-24, 36, -27, 13, -6, 3, -1},
  {182, -354, 330, -198, 85, -28, 10, -4, 1},
  {-1730, 4090, -4480, 3120, -1595, 631, -195, 50, -15, 5, -1},
  {19802, -55270, 70430, -55730, 31630, -14018, 5101, -1536, 375, -80, 21, -6, 1},
  {-264334, 850990, -1246504, 1121960, -711480, 345268, -135639, 44997, -12922, 3171, -644, 119, -28, 7, -1},
  ...
		

References

  • A. Messiah, Quantum mechanics, vol. 2, page 712, 795-800, North Holland, 1969.

Programs

  • Mathematica
    p[t_, x_] = FullSimplify[Exp[t*x]/(t - x - Exp[ -2*t] + 2*Exp[ -t])] g = Table[ FullSimplify[ExpandAll[n!*(1 - x)^(n + 1)*SeriesCoefficient[ Series[p[t, x], {t, 0, 30}], n]]], {n, 0, 10}]; a = Table[CoefficientList[FullSimplify[ExpandAll[n!*(1 - x)^(n + 1)*SeriesCoefficient[Series[p[t, x], {t, 0, 30}], n]]], x], {n, 0, 10}]; Flatten[a]

Formula

p(t,x)=Exp[t*x]/(t - x - Exp[ -2*t] + 2*Exp[ -t])=sum(P(x,n)*t^n/n!,m{n,0,Infinity}); out_n,m=Coefficients(n!*(1-x)^(n+1)*P(x,n)).

A165233 Signed denominators of terms in series expansion of cos(x)+sin(x).

Original entry on oeis.org

1, 1, -2, -6, 24, 120, -720, -5040, 40320, 362880, -3628800, -39916800, 479001600, 6227020800, -87178291200, -1307674368000, 20922789888000, 355687428096000, -6402373705728000, -121645100408832000, 2432902008176640000
Offset: 0

Views

Author

Jaume Oliver Lafont, Sep 09 2009

Keywords

Comments

Sum(n>=0,1/a(n))=cos(1)+sin(1).
Sum(n>=0,(Pi/4)^n/a(n))=sqrt(2).
Numerators are in A000012. - Alois P. Heinz, Jan 20 2016

Crossrefs

Programs

  • Mathematica
    Sign@ # Denominator@ # & /@ CoefficientList[Series[Cos@ x + Sin@ x, {x, 0, 20}], x] (* Michael De Vlieger, Oct 08 2016 *)
  • PARI
    a(n)=(-1)^(n\2)*n!

Formula

a(n)=(-1)^floor(n/2)*n! = A057077(n)*A000142(n).
a(n)=(sin(n*Pi/2)+cos(n*Pi/2))*n!.
a(n)=sqrt(2)*sin((2n+1)*Pi/4)*n!.
a(n)=sqrt(2)*cos((2n-1)*Pi/4)*n!.
G.f. Q(0) where Q(k)= 1 + x*(4*k+1)/(1 + 2*x*(2*k+1)/(1 - 2*x*(2*k+1) - x*(4*k+3)/(1 + x*(4*k+3) - 4*x*(k+1)/(4*x*(k+1) - 1/Q(k+1))))); (continued fraction, 3rd kind, 5-step). - Sergei N. Gladkovskii, Aug 15 2012
E.g.f.: (1 + x)/(1 + x^2). - Ilya Gutkovskiy, Oct 08 2016

A358624 Triangle read by rows. The coefficients of the Hahn polynomials in ascending order of powers. T(n, k) = n! * [x^k] hypergeom([-x, -n, n + 1], [1, 1], 1).

Original entry on oeis.org

1, 1, 2, 2, 6, 6, 6, 22, 30, 20, 24, 100, 170, 140, 70, 120, 548, 1050, 1120, 630, 252, 720, 3528, 7476, 8820, 6720, 2772, 924, 5040, 26136, 59388, 78708, 64680, 37884, 12012, 3432, 40320, 219168, 529896, 748440, 704550, 432432, 204204, 51480, 12870
Offset: 0

Views

Author

Peter Luschny, Nov 26 2022

Keywords

Examples

			[0]     1;
[1]     1,      2;
[2]     2,      6,      6;
[3]     6,     22,     30,     20;
[4]    24,    100,    170,    140,     70;
[5]   120,    548,   1050,   1120,    630,    252;
[6]   720,   3528,   7476,   8820,   6720,   2772,    924;
[7]  5040,  26136,  59388,  78708,  64680,  37884,  12012,  3432;
[8] 40320, 219168, 529896, 748440, 704550, 432432, 204204, 51480, 12870;
		

References

  • A. F. Nikiforov, S. K. Suslov, and V. B. Uvarov, Classical Orthogonal Polynomials of a Discrete Variable, Springer-Verlag Berlin Heidelberg, 1991.

Crossrefs

Cf. A000142, A000984, A001564 (row sums), A133942 (alternating row sums).

Programs

  • Maple
    H := (n, x) -> n!*hypergeom([-x, -n, n + 1], [1, 1], 1):
    for n from 0 to 8 do seq(coeff(simplify(H(n, x)), x, k), k = 0..n) od;

Formula

The general formula for the Hahn polynomials is H(n, x, N, a, b) = (-1)^n*(Pochhammer(N-n, n)*Pochhammer(b+1, n) / n!)*hypergeom([-n, -x, a + b + n + 1], [b + 1, 1 - N], 1). We consider here the case N = a = b = 0.
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