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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A258878 E.g.f.: S(x) = Series_Reversion( Integral 1/(1-x^3)^(1/3) dx ), where the constant of integration is zero.

Original entry on oeis.org

1, -2, -20, -3320, -1598960, -1757280800, -3687555924800, -13169930119702400, -73877683147510880000, -613509458527719828800000, -7207218902820454669458560000, -115535941439664355284062432000000, -2454583328787383660694513356633600000, -67459240631654340522067311327301145600000
Offset: 1

Views

Author

Paul D. Hanna, Jun 13 2015

Keywords

Examples

			E.g.f. with offset 0 is C(x) and e.g.f. with offset 1 is S(x) where:
C(x) = 1 - 2*x^3/3! - 20*x^6/6! - 3320*x^9/9! - 1598960*x^12/12! - 1757280800*x^15/15! - 3687555924800*x^18/18! -...
S(x) = x - 2*x^4/4! - 20*x^7/7! - 3320*x^10/10! - 1598960*x^13/13! - 1757280800*x^16/16! - 3687555924800*x^19/19! -...
such that C(x)^3 + S(x)^3 = 1:
C(x)^3 = 1 - 6*x^3/3! + 180*x^6/6! - 3240*x^9/9! + 641520*x^12/12! + 455479200*x^15/15! + 798961838400*x^18/18! +...
S(x)^3 = 6*x^3/3! - 180*x^6/6! + 3240*x^9/9! - 641520*x^12/12! - 455479200*x^15/15! - 798961838400*x^18/18! -...
Related Expansions.
(1) The series reversion of S(x) is Integral 1/(1-x^3)^(1/3) dx:
Series_Reversion(S(x)) = x + 2*x^4/4! + 160*x^7/7! + 62720*x^10/10! +...
1/(1-x^3)^(1/3) = 1 + 2*x^3/3! + 160*x^6/6! + 62720*x^9/9! + 68992000*x^12/12! + 163235072000*x^15/15! +...+ A178575(n)*x^(3*n)/(3*n)! +...
(2) C(x)^2*C'(x) = -S(x)^2*S'(x) = 0, where:
C(x)^2*C'(x) = -2*x^2/2! + 60*x^5/5! - 1080*x^8/8! + 213840*x^11/11! + 151826400*x^14/14! + 266320612800*x^17/17! -...
S(x)^2*S'(x) = 2*x^2/2! - 60*x^5/5! + 1080*x^8/8! - 213840*x^11/11! - 151826400*x^14/14! - 266320612800*x^17/17! -...
(3) d/dx C(x)^2 = -2*S(x)^2, where:
C(x)^2 = 1 - 4*x^3/3! + 40*x^6/6! + 80*x^9/9! + 93280*x^12/12! + 60209600*x^15/15! + 83885507200*x^18/18! +...
S(x)^2 = 2*x^2/2! - 20*x^5/5! - 40*x^8/8! - 46640*x^11/11! - 30104800*x^14/14! - 41942753600*x^17/17! -...
(4) d/dx S(x)/C(x) = 1/C(x)^3:
1/C(x) = 1 + 2*x^3/3! + 100*x^6/6! + 23480*x^9/9! + 15238960*x^12/12! + 21091796000*x^15/15! + 53393583707200*x^18/18! +...
1/C(x)^3 = 1 + 6*x^3/3! + 540*x^6/6! + 184680*x^9/9! + 157600080*x^12/12! +...
S(x)/C(x) = x + 6*x^4/4! + 540*x^7/7! + 184680*x^10/10! + 157600080*x^13/13! + 270419925600*x^16/16! +...+  A258880(n)*x^(3*n+1)/(3*n+1)! +...
where
Series_Reversion(S(x)/C(x)) = x - x^4/4 + x^7/7 - x^10/10 + x^13/13 - x^16/16 +...

Crossrefs

Cf. A178575, A258880.

Programs

  • PARI
    /* E.g.f. Series_Reversion(Integral 1/(1-x^3)^(1/3) dx): */
{a(n)=local(S=x,C=1+x); S = serreverse( intformal(  1/(1-x^3 +x*O(x^(3*n)))^(1/3) )); (3*n+1)!*polcoeff(S,3*n+1)}
for(n=0,15,print1(a(n),", "))
  • PARI
    /* E.g.f. C(x) with offset 0: */
{a(n)=local(S=x,C=1+x);for(i=1,n,S=intformal(C +x*O(x^(3*n)));C=1-intformal(S^2/C +x*O(x^(3*n)));); (3*n)!*polcoeff(C,3*n)}
for(n=0,15,print1(a(n),", "))
  • PARI
    /* E.g.f. S(x) with offset 1: */
{a(n)=local(S=x,C=1+x);for(i=1,n+1,S=intformal(C +x*O(x^(3*n)));C=1-intformal(S^2/C +x*O(x^(3*n+1)));); (3*n+1)!*polcoeff(S,3*n+1)}
for(n=0,15,print1(a(n),", "))

Formula

E.g.f.: S(x) = Series_Reversion( Sum_{n>=0} A178575(n)*x^(3*n+1)/(3*n+1)! ).
E.g.f.: Let C(x) = Sum_{n>=0} a(n)*x^(3*n)/(3*n)! and S(x) = Sum_{n>=0} a(n)*x^(3*n+1)/(3*n+1)! then C(x) and S(x) satisfy:
(1) C(x)^3 + S(x)^3 = 1,
(2) S'(x) = C(x),
(3) C'(x) = -S(x)^2/C(x),
(4) C(x)^2 * C'(x) + S(x)^2 * S'(x) = 0,
(5) S(x)/C(x) = Integral 1/C(x)^3 dx,
(6) S(x)/C(x) = Series_Reversion( Integral 1/(1+x^3) dx ) = Series_Reversion( Sum_{n>=0} (-1)^n * x^(3*n+1)/(3*n+1) ).

A357541 Coefficients T(n,k) of x^(3*n)*r^(3*k)/(3*n)! in power series C(x,r) = 1 + Integral S(x,r)^2 * D(x,r)^2 dx such that C(x,r)^3 - S(x,r)^3 = 1 and D(x,r)^3 - r^3*S(x,r)^3 = 1, as a triangle read by rows.

Original entry on oeis.org

1, 2, 0, 40, 120, 0, 3680, 37440, 21600, 0, 880000, 20592000, 38966400, 8553600, 0, 435776000, 19269888000, 79491456000, 57708288000, 6329664000, 0, 386949376000, 28748332800000, 213892766208000, 335872728576000, 123646051584000, 7852204800000, 0, 560034421760000, 64544356546560000, 774705298498560000, 2169194182594560000, 1730103155573760000, 374841224017920000, 15132769090560000, 0
Offset: 0

Views

Author

Paul D. Hanna, Oct 09 2022

Keywords

Comments

Related to Dixon elliptic function cm(x,0) (cf. A104134).
Equals a row reversal of triangle A357542, which describes the related function D(x,r).

Examples

			E.g.f.: C(x,r) = Sum_{n>=0} Sum_{k=0..n} T(n,k) * x^(3*n) * r^(3*k) / (3*n)! begins:
C(x,r) = 1 + Integral S(x,r)^2 * D(x,r)^2 dx = 1 + 2*x^3/3! + (40 + 120*r^3)*x^6/6! + (3680 + 37440*r^3 + 21600*r^6)*x^9/9! + (880000 + 20592000*r^3 + 38966400*r^6 + 8553600*r^9)*x^12/12! + (435776000 + 19269888000*r^3 + 79491456000*r^6 + 57708288000*r^9 + 6329664000*r^12)*x^15/15! + (386949376000 + 28748332800000*r^3 + 213892766208000*r^6 + 335872728576000*r^9 + 123646051584000*r^12 + 7852204800000*r^15)*x^18/18! + (560034421760000 + 64544356546560000*r^3 + 774705298498560000*r^6 + 2169194182594560000*r^9 + 1730103155573760000*r^12 + 374841224017920000*r^15 + 15132769090560000*r^18)*x^21/21! + ...
This table of coefficients T(n,k) of x^(3*n) * r^(3*k) / (3*n)! in C(x,r) for n >= 0, k = 0..n, begins:
n = 0: [1];
n = 1: [2, 0];
n = 2: [40, 120, 0];
n = 3: [3680, 37440, 21600, 0];
n = 4: [880000, 20592000, 38966400, 8553600, 0];
n = 5: [435776000, 19269888000, 79491456000, 57708288000, 6329664000, 0];
n = 6: [386949376000, 28748332800000, 213892766208000, 335872728576000, 123646051584000, 7852204800000, 0];
n = 7: [560034421760000, 64544356546560000, 774705298498560000, 2169194182594560000, 1730103155573760000, 374841224017920000, 15132769090560000, 0];
n = 8: [1233482823823360000, 208114576947425280000, 3741268129758720000000, 16693947940315852800000, 23676862831649280000000, 11169319418477383680000, 1563368171330211840000, 42815371615948800000, 0];
...
in which column 0 gives the unsigned coefficients in the Dixon elliptic function cm(x,0) (cf. A104134).
RELATED SERIES.
S(x,r) = Integral C(x,r)^2 * D(x,r)^2 dx = x + (4 + 4*r^3)*x^4/4! + (160 + 800*r^3 + 160*r^6)*x^7/7! + (20800 + 292800*r^3 + 292800*r^6 + 20800*r^9)*x^10/10! + (6476800 + 191910400*r^3 + 500121600*r^6 + 191910400*r^9 + 6476800*r^12)*x^13/13! + (3946624000 + 210590336000*r^3 + 1091343616000*r^6 + 1091343616000*r^9 + 210590336000*r^12 + 3946624000*r^15)*x^16/16! + (4161608704000 + 361556726784000*r^3 + 3216369361920000*r^6 + 6333406238720000*r^9 + 3216369361920000*r^12 + 361556726784000*r^15 + 4161608704000*r^18)*x^19/19! + (6974121256960000 + 919365914368000000*r^3 + 12789764316088320000*r^6 + 42703786876467200000*r^9 + 42703786876467200000*r^12 + 12789764316088320000*r^15 + 919365914368000000*r^18 + 6974121256960000*r^21)*x^22/22! + ...
where C(x,r)^3 - S(x,r)^3 = 1.
D(x,r) = 1 + r^3 * Integral S(x,r)^2 * C(x,r)^2 dx = 1 + 2*r^3*x^3/3! + (120*r^3 + 40*r^6)*x^6/6! + (21600*r^3 + 37440*r^6 + 3680*r^9)*x^9/9! + (8553600*r^3 + 38966400*r^6 + 20592000*r^9 + 880000*r^12)*x^12/12! + (6329664000*r^3 + 57708288000*r^6 + 79491456000*r^9 + 19269888000*r^12 + 435776000*r^15)*x^15/15! + (7852204800000*r^3 + 123646051584000*r^6 + 335872728576000*r^9 + 213892766208000*r^12 + 28748332800000*r^15 + 386949376000*r^18)*x^18/18! + (15132769090560000*r^3 + 374841224017920000*r^6 + 1730103155573760000*r^9 + 2169194182594560000*r^12 + 774705298498560000*r^15 + 64544356546560000*r^18 + 560034421760000*r^21)*x^21/21! + ...
where D(x,r)^3 - r^3 * C(x,r)^3 = (1 - r^3).

Links

Crossrefs

Cf. A104134 (cm(x,0)), A357540 (S(x,r)), A357542 (D(x,r)), A178575 (row sums), A357545 (central terms).
Cf. A357801.

Programs

  • PARI
    {T(n,k) = my(S=x,C=1,D=1); for(i=0,n,
S = intformal( C^2*D^2 +O(x^(3*n+3)));
C = 1 + intformal( S^2*D^2);
D = 1 + r^3*intformal( S^2*C^2); );
(3*n)!*polcoeff( polcoeff(C,3*n,x),3*k,r)}
for(n=0,10, for(k=0,n, print1( T(n,k),", "));print(""))
  • PARI
    /* Using Series Reversion for S(x,r) (faster) */
{T(n,k) = my(S = serreverse( intformal( 1/((1 + x^3)^2*(1 + r^3*x^3)^2 +O(x^(3*n+3)) )^(1/3) )) );
(3*n)!*polcoeff( polcoeff((1 + S^3)^(1/3),3*n,x),3*k,r)}
for(n=0,10, for(k=0,n, print1( T(n,k),", "));print(""))

Formula

Generating function C(x,r) = Sum_{n>=0} Sum_{k=0..n} T(n,k) * x^(3*n) * r^(3*k) / (3*n)! and related functions S(x,r) and D(x,r) satisfy the following formulas.
For brevity, some formulas here will use S = S(x,r), C = C(x,r), and D = D(x,r).
(1.a) C(x,r)^3 - S(x,r)^3 = 1.
(1.b) D(x,r)^3 - r^3 * S(x,r)^3 = 1.
(1.c) D(x,r)^3 - r^3 * C(x,r)^3 = 1 - r^3.
Integral formulas.
(2.a) S(x,r) = Integral C(x,r)^2 * D(x,r)^2 dx.
(2.b) C(x,r) = 1 + Integral S(x,r)^2 * D(x,r)^2 dx.
(2.c) D(x,r) = 1 + r^3 * Integral S(x,r)^2 * C(x,r)^2 dx.
(2.d) C(x,r)^3 = 1 + 3 * Integral S(x,r)^2 * C(x,r)^2 * D(x,r)^2 dx.
Derivatives.
(3.a) d/dx S(x,r) = C(x,r)^2 * D(x,r)^2.
(3.b) d/dx C(x,r) = S(x,r)^2 * D(x,r)^2.
(3.c) d/dx D(x,r) = r^3 * S(x,r)^2 * C(x,r)^2.
Exponential formulas.
(4.a) C - S = exp( -Integral (C + S) * D^2 dx ).
(4.b) D - r*S = exp( -r * Integral (D + r*S) * C^2 dx ).
(4.c) C + S = sqrt(C^2 - S^2) * exp( Integral D^2/(C^2 - S^2) dx ).
(4.d) D + r*S = sqrt(D^2 - r^2*S^2) * exp( r * Integral C^2/(D^2 - r^2*S^2) dx ).
(5.a) C^2 - S^2 = exp( -2 * Integral S*C/(C + S) * D^2 dx ).
(5.b) D^2 - r^2*S^2 = exp( -2*r^2 * Integral S*D/(D + r*S) * C^2 dx ).
(5.c) C^2 + S^2 = exp( 2 * Integral S*C*(C + S)/(C^2 + S^2) * D^2 dx ).
(5.d) D^2 + r^2*S^2 = exp( 2*r^2 * Integral S*D*(D + r*S)/(D^2 + r^2*S^2) * C^2 dx ).
Hyperbolic functions.
(6.a) C = sqrt(C^2 - S^2) * cosh( Integral D^2/(C^2 - S^2) dx ).
(6.b) S = sqrt(C^2 - S^2) * sinh( Integral D^2/(C^2 - S^2) dx ).
(6.c) D = sqrt(D^2 - r^2*S^2) * cosh( r * Integral C^2/(D^2 - r^2*S^2) dx ).
(6.d) r*S = sqrt(D^2 - r^2*S^2) * sinh( r * Integral C^2/(D^2 - r^2*S^2) dx ).
Other formulas.
(7) S(x,r) = Series_Reversion( Integral 1/((1 + x^3)*(1 + r^3*x^3))^(2/3) dx ).
(8.a) T(n,0) = (-1)^n * A104134(n).
(8.b) Sum_{k=0..n} T(n,k) = (3*n)!/(3^n*n!) * Product_{k=1..n} (3*k - 2) = A178575(n), for n >= 0.
From Paul D. Hanna, Apr 14 2023 (Start):
Let F(x,r) = Integral 1/((1 + x^3)*(1 + r^3*x^3))^(2/3) dx, then
(9.a) S( F(x,r), r) = x,
(9.b) C( F(x,r), r) = (1 + x^3)^(1/3),
(9.c) D( F(x,r), r) = (1 + r^3*x^3)^(1/3). (End)

A357542 Coefficients T(n,k) of x^(3*n)*r^(3*k)/(3*n)! in power series D(x,r) = 1 + r^3 * Integral S(x,r)^2 * D(x,r)^2 dx such that C(x,r)^3 - S(x,r)^3 = 1 and D(x,r)^3 - r^3*S(x,r)^3 = 1, as a triangle read by rows.

Original entry on oeis.org

1, 0, 2, 0, 120, 40, 0, 21600, 37440, 3680, 0, 8553600, 38966400, 20592000, 880000, 0, 6329664000, 57708288000, 79491456000, 19269888000, 435776000, 0, 7852204800000, 123646051584000, 335872728576000, 213892766208000, 28748332800000, 386949376000, 0, 15132769090560000, 374841224017920000, 1730103155573760000, 2169194182594560000, 774705298498560000, 64544356546560000, 560034421760000
Offset: 0

Views

Author

Paul D. Hanna, Oct 09 2022

Keywords

Comments

Related to Dixon elliptic function cm(x,0) (cf. A104134).
Equals a row reversal of triangle A357541 which describes the related function C(x,r).

Examples

			E.g.f.: D(x,r) = Sum_{n>=0} Sum_{k=0..n} T(n,k) * x^(3*n) * r^(3*k) / (3*n)! begins:
D(x,r) = 1 + r^3 * Integral S(x,r)^2 * C(x,r)^2 dx = 1 + 2*r^3*x^3/3! + (120*r^3 + 40*r^6)*x^6/6! + (21600*r^3 + 37440*r^6 + 3680*r^9)*x^9/9! + (8553600*r^3 + 38966400*r^6 + 20592000*r^9 + 880000*r^12)*x^12/12! + (6329664000*r^3 + 57708288000*r^6 + 79491456000*r^9 + 19269888000*r^12 + 435776000*r^15)*x^15/15! + (7852204800000*r^3 + 123646051584000*r^6 + 335872728576000*r^9 + 213892766208000*r^12 + 28748332800000*r^15 + 386949376000*r^18)*x^18/18! + (15132769090560000*r^3 + 374841224017920000*r^6 + 1730103155573760000*r^9 + 2169194182594560000*r^12 + 774705298498560000*r^15 + 64544356546560000*r^18 + 560034421760000*r^21)*x^21/21! + ...
This table of coefficients T(n,k) of x^(3*n) * r^(3*k) / (3*n)! in C(x,r) for n >= 0, k = 0..n, begins:
n = 0: [1];
n = 1: [0, 2];
n = 2: [0, 120, 40];
n = 3: [0, 21600, 37440, 3680];
n = 4: [0, 8553600, 38966400, 20592000, 880000];
n = 5: [0, 6329664000, 57708288000, 79491456000, 19269888000, 435776000];
n = 6: [0, 7852204800000, 123646051584000, 335872728576000, 213892766208000, 28748332800000, 386949376000];
n = 7: [0, 15132769090560000, 374841224017920000, 1730103155573760000, 2169194182594560000, 774705298498560000, 64544356546560000, 560034421760000];
n = 8: [0, 42815371615948800000, 1563368171330211840000, 11169319418477383680000, 23676862831649280000000, 16693947940315852800000, 3741268129758720000000, 208114576947425280000, 1233482823823360000];
...
in which the main diagonal gives the unsigned coefficients in the Dixon elliptic function cm(x,0) (cf. A104134).
RELATED SERIES.
S(x,r) = Integral C(x,r)^2 * D(x,r)^2 dx = x + (4 + 4*r^3)*x^4/4! + (160 + 800*r^3 + 160*r^6)*x^7/7! + (20800 + 292800*r^3 + 292800*r^6 + 20800*r^9)*x^10/10! + (6476800 + 191910400*r^3 + 500121600*r^6 + 191910400*r^9 + 6476800*r^12)*x^13/13! + (3946624000 + 210590336000*r^3 + 1091343616000*r^6 + 1091343616000*r^9 + 210590336000*r^12 + 3946624000*r^15)*x^16/16! + (4161608704000 + 361556726784000*r^3 + 3216369361920000*r^6 + 6333406238720000*r^9 + 3216369361920000*r^12 + 361556726784000*r^15 + 4161608704000*r^18)*x^19/19! + (6974121256960000 + 919365914368000000*r^3 + 12789764316088320000*r^6 + 42703786876467200000*r^9 + 42703786876467200000*r^12 + 12789764316088320000*r^15 + 919365914368000000*r^18 + 6974121256960000*r^21)*x^22/22! + ...
where D(x,r)^3 - r^3 * S(x,r)^3 = 1.
C(x,r) = 1 + Integral S(x,r)^2 * D(x,r)^2 dx = 1 + 2*x^3/3! + (40 + 120*r^3)*x^6/6! + (3680 + 37440*r^3 + 21600*r^6)*x^9/9! + (880000 + 20592000*r^3 + 38966400*r^6 + 8553600*r^9)*x^12/12! + (435776000 + 19269888000*r^3 + 79491456000*r^6 + 57708288000*r^9 + 6329664000*r^12)*x^15/15! + (386949376000 + 28748332800000*r^3 + 213892766208000*r^6 + 335872728576000*r^9 + 123646051584000*r^12 + 7852204800000*r^15)*x^18/18! + (560034421760000 + 64544356546560000*r^3 + 774705298498560000*r^6 + 2169194182594560000*r^9 + 1730103155573760000*r^12 + 374841224017920000*r^15 + 15132769090560000*r^18)*x^21/21! + ...
where D(x,r)^3 - r^3 * C(x,r)^3 = (1 - r^3).

Links

Crossrefs

Cf. A104134 (cm(x,0)), A357540 (S(x,r)), A357541 (C(x,r)), A178575 (row sums), A357545 (central terms).
Cf. A357802.

Programs

  • PARI
    {T(n,k) = my(S=x,C=1,D=1); for(i=0,n,
S = intformal( C^2*D^2 +O(x^(3*n+3)));
C = 1 + intformal( S^2*D^2);
D = 1 + r^3*intformal( S^2*C^2); );
(3*n)!*polcoeff( polcoeff(D,3*n,x),3*k,r)}
for(n=0,10, for(k=0,n, print1( T(n,k),", "));print(""))
  • PARI
    /* Using Series Reversion for S(x,r) (faster) */
{T(n,k) = my(S = serreverse( intformal( 1/((1 + x^3)^2*(1 + r^3*x^3)^2 +O(x^(3*n+3)) )^(1/3) )) );
(3*n)!*polcoeff( polcoeff((1 + r^3*S^3)^(1/3),3*n,x),3*k,r)}
for(n=0,10, for(k=0,n, print1( T(n,k),", "));print(""))

Formula

Generating function D(x,r) = Sum_{n>=0} Sum_{k=0..n} T(n,k) * x^(3*n) * r^(3*k) / (3*n)! and related functions S(x,r) and C(x,r) satisfy the following relations.
For brevity, some formulas here will use S = S(x,r), C = C(x,r), and D = D(x,r).
(1.a) C(x,r)^3 - S(x,r)^3 = 1.
(1.b) D(x,r)^3 - r^3 * S(x,r)^3 = 1.
(1.c) D(x,r)^3 - r^3 * C(x,r)^3 = 1 - r^3.
Integral formulas.
(2.a) S(x,r) = Integral C(x,r)^2 * D(x,r)^2 dx.
(2.b) C(x,r) = 1 + Integral S(x,r)^2 * D(x,r)^2 dx.
(2.c) D(x,r) = 1 + r^3 * Integral S(x,r)^2 * C(x,r)^2 dx.
(2.d) D(x,r)^3 = 1 + r^3 * Integral 3 * S(x,r)^2 * C(x,r)^2 * D(x,r)^2 dx.
Derivatives.
(3.a) d/dx S(x,r) = C(x,r)^2 * D(x,r)^2.
(3.b) d/dx C(x,r) = S(x,r)^2 * D(x,r)^2.
(3.c) d/dx D(x,r) = r^3 * S(x,r)^2 * C(x,r)^2.
Exponential formulas.
(4.a) C - S = exp( -Integral (C + S) * D^2 dx ).
(4.b) D - r*S = exp( -r * Integral (D + r*S) * C^2 dx ).
(4.c) C + S = sqrt(C^2 - S^2) * exp( Integral D^2/(C^2 - S^2) dx ).
(4.d) D + r*S = sqrt(D^2 - r^2*S^2) * exp( r * Integral C^2/(D^2 - r^2*S^2) dx ).
(5.a) C^2 - S^2 = exp( -2 * Integral S*C/(C + S) * D^2 dx ).
(5.b) D^2 - r^2*S^2 = exp( -2*r^2 * Integral S*D/(D + r*S) * C^2 dx ).
(5.c) C^2 + S^2 = exp( 2 * Integral S*C*(C + S)/(C^2 + S^2) * D^2 dx ).
(5.d) D^2 + r^2*S^2 = exp( 2*r^2 * Integral S*D*(D + r*S)/(D^2 + r^2*S^2) * C^2 dx ).
Hyperbolic functions.
(6.a) C = sqrt(C^2 - S^2) * cosh( Integral D^2/(C^2 - S^2) dx ).
(6.b) S = sqrt(C^2 - S^2) * sinh( Integral D^2/(C^2 - S^2) dx ).
(6.c) D = sqrt(D^2 - r^2*S^2) * cosh( r * Integral C^2/(D^2 - r^2*S^2) dx ).
(6.d) r*S = sqrt(D^2 - r^2*S^2) * sinh( r * Integral C^2/(D^2 - r^2*S^2) dx ).
Other formulas.
(7) S(x,r) = Series_Reversion( Integral ( (1 + x^3)^2 * (1 + r^3*x^3)^2 )^(-1/3) dx ).
(8.a) T(n,n) = (-1)^n * A104134(n).
(8.b) Sum_{k=0..n} T(n,k) = (3*n)!/(3^n*n!) * Product_{k=1..n} (3*k - 2) = A178575(n), for n >= 0.

A357543 a(n) = (3*n+1)!/(3^n*n!) * Product_{k=1..n} (3*k - 2), for n >= 0.

Original entry on oeis.org

1, 8, 1120, 627200, 896896000, 2611761152000, 13497581633536000, 112839782456360960000, 1427423248072966144000000, 25979103114927983820800000000, 653945983608967208737177600000000, 22056290135163246016287526092800000000, 971138454651237722097139773865984000000000
Offset: 0

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Author

Paul D. Hanna, Oct 10 2022

Keywords

Comments

Equals row sums of triangle A357540.
a(n) = (3*n+1) * A178575(n) for n >= 0.

Crossrefs

Cf. A357540, A178575, A004117.

Programs

  • PARI
    {a(n) = (3*n+1)!/(3^n*n!) * prod(k=1, n, 3*k-2)}
for(n=0,20, print1(a(n),", "))

Formula

E.g.f.: Sum_{n>=0} a(n) * x^(3*n+1) / (3*n+1)! = x/(1 - x^3)^(1/3).
a(n) ~ sqrt(2*Pi) * 3^(3*n + 3/2) * n^(3*n + 5/6) / (Gamma(1/3) * exp(3*n)). - Vaclav Kotesovec, Oct 10 2022
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