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 1-3 of 3 results.

A234313 E.g.f. satisfies: A'(x) = A(x)^5 * A(-x) with A(0) = 1.

Original entry on oeis.org

1, 1, 4, 34, 376, 5896, 107104, 2445664, 61835776, 1853785216, 60075541504, 2229983878144, 88157067006976, 3901637972801536, 182049480718741504, 9356335870657921024, 503257631887961522176, 29455739077723718189056, 1794347026494847887867904, 117825990265521485020463104
Offset: 0

Views

Author

Paul D. Hanna, Jan 07 2014

Keywords

Examples

			E.g.f.: A(x) = 1 + x + 4*x^2/2! + 34*x^3/3! + 376*x^4/4! + 5896*x^5/5! +...
Related series.
A(x)^5 = 1 + 5*x + 40*x^2/2! + 470*x^3/3! + 7120*x^4/4! + 134000*x^5/5! +...
A(x)^3 = 1 + 3*x + 18*x^2/2! + 180*x^3/3! + 2376*x^4/4! + 40608*x^5/5! +...
Note that 1 - 1/A(x)^3 is an odd function:
1 - 1/A(x)^3 = 3*x + 18*x^3/3! + 1728*x^5/5! + 496368*x^7/7! + 287929728*x^9/9! +...
where Series_Reversion((1 - 1/A(x)^3)/3) = Integral (1-9*x^2)^(1/3) dx.
		

Crossrefs

Programs

  • Mathematica
    CoefficientList[1/(1 - 3*InverseSeries[Series[Integrate[(1-9*x^2)^(1/3),x],{x,0,20}],x])^(1/3),x] * Range[0,20]! (* Vaclav Kotesovec, Jan 28 2014 *)
  • PARI
    {a(n)=local(A=1); for(i=0, n, A=1+intformal(A^5*subst(A, x, -x) +x*O(x^n) )); n!*polcoeff(A, n)}
    for(n=0, 20, print1(a(n), ", "))
    
  • PARI
    {a(n)=local(A=1); A=1/(1-3*serreverse(intformal((1-9*x^2 +x*O(x^n))^(1/3))))^(1/3); n!*polcoeff(A, n)}
    for(n=0, 20, print1(a(n), ", "))

Formula

E.g.f.: 1/(1 - 3*Series_Reversion( Integral (1-9*x^2)^(1/3) dx ))^(1/3).
Limit n->infinity (a(n)/n!)^(1/n) = 15*GAMMA(5/6) / (sqrt(Pi)*GAMMA(1/3)) = 3.565870639063299... - Vaclav Kotesovec, Jan 28 2014

A235329 E.g.f. satisfies: A'(x) = A(x)^3 / A(-x) with A(0) = 1.

Original entry on oeis.org

1, 1, 4, 22, 184, 1888, 24352, 364336, 6372352, 125098624, 2765195776, 67161837568, 1795080211456, 51946830487552, 1628857441189888, 54705106541123584, 1968709261466042368, 75262309701303402496, 3057220808668673081344, 131069643224297960046592
Offset: 0

Views

Author

Paul D. Hanna, Jan 05 2014

Keywords

Examples

			E.g.f.: A(x) = 1 + x + 4*x^2/2! + 22*x^3/3! + 184*x^4/4! + 1888*x^5/5! +...
Related series.
A(x)^3 = 1 + 3*x + 18*x^2/2! + 144*x^3/3! + 1512*x^4/4! + 19224*x^5/5! +...
Note that 1 - 1/A(x)^3 is an odd function:
1 - 1/A(x)^3 = 3*x - 18*x^3/3! - 216*x^5/5! - 18144*x^7/7! - 3483648*x^9/9! +...
where Series_Reversion((1 - 1/A(x)^3)/3) = Integral 1/(1-9*x^2)^(1/3) dx.
		

Crossrefs

Programs

  • Mathematica
    CoefficientList[1/(1 - 3*InverseSeries[Series[Integrate[1/(1-9*x^2)^(1/3),x],{x,0,20}],x])^(1/3),x] * Range[0,20]! (* Vaclav Kotesovec, Jan 28 2014 *)
  • PARI
    /* By definition A'(x) = A(x)^3 / A(-x): */
    {a(n)=local(A=1); for(i=0, n, A=1+intformal(A^3/subst(A, x, -x) +x*O(x^n) )); n!*polcoeff(A, n)}
    for(n=0, 25, print1(a(n), ", "))
    
  • PARI
    /* E.g.f. 1/(1 - 3*Series_Reversion(Integral (1-9*x)^(1/3) dx))^(1/3): */
    {a(n)=local(A=1);A=1/(1-3*serreverse(intformal(1/(1-9*x^2 +x*O(x^n))^(1/3))))^(1/3);n!*polcoeff(A, n)}
    for(n=0,25,print1(a(n),", "))

Formula

E.g.f.: 1/(1 - 3*Series_Reversion( Integral 1/(1-9*x^2)^(1/3) dx ))^(1/3).
Limit n->infinity (a(n)/n!)^(1/n) = Pi*2^(5/3)/(sqrt(3)*GAMMA(2/3)^3) = 2.3191905339278567... - Vaclav Kotesovec, Jan 28 2014

A235321 E.g.f. satisfies: A'(x) = A(x)^4 * A(-x)^2 with A(0) = 1.

Original entry on oeis.org

1, 1, 2, 10, 56, 496, 4592, 58240, 753536, 12428416, 206700032, 4194910720, 85291222016, 2054623707136, 49390297628672, 1376983620812800, 38210541166493696, 1209980100295622656, 38070418025153626112, 1349585751030491054080, 47479274652991633227776
Offset: 0

Views

Author

Paul D. Hanna, Jan 05 2014

Keywords

Examples

			E.g.f.: A(x) = 1 + x + 2*x^2/2! + 10*x^3/3! + 56*x^4/4! + 496*x^5/5! +...
Related series.
A(x)^2 = 1 + 2*x + 6*x^2/2! + 32*x^3/3! + 216*x^4/4! + 1952*x^5/5! +...
A(x)^4 = 1 + 4*x + 20*x^2/2! + 136*x^3/3! + 1160*x^4/4! + 12064*x^5/5! +...
A(x)^5 = 1 + 5*x + 30*x^2/2! + 230*x^3/3! + 2160*x^4/4! + 24200*x^5/5! +...
where 3 - 15*A(x) + 20*A(x)^2 = (8 - 15*x)*A(x)^5.
Note that 1 - 1/A(x) is an odd function that begins:
1 - 1/A(x) = x + 4*x^3/3! + 136*x^5/5! + 12544*x^7/7! + 2240896*x^9/9! +...
where Series_Reversion(1 - 1/A(x)) = x - 2*x^3/3 + x^5/5.
		

Crossrefs

Cf. A235322.

Programs

  • Mathematica
    CoefficientList[1/(1 - InverseSeries[Series[x - 2*x^3/3 + x^5/5, {x, 0, 20}], x]),x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 28 2014 *)
  • PARI
    /* By definition, A'(x) = A(x)^4 * A(-x)^2: */
    {a(n)=local(A=1); for(i=0, n, A=1+intformal(A^4*subst(A,x,-x)^2 +x*O(x^n) )); n!*polcoeff(A, n)}
    for(n=0,25,print1(a(n),", "))
    
  • PARI
    /* By equation: 3 - 15*A(x) + 20*A(x)^2 - (8 - 15*x)*A(x)^5 = 0 */
    {a(n)=local(A=1);for(i=0,n,A=(3+20*A^2-(8-15*x)*A^5)/15 +x*O(x^n));n!*polcoeff(A,n)}
    for(n=0,25,print1(a(n),", "))
    
  • PARI
    /* E.g.f. 1/(1 - Series_Reversion(Integral (1-x^2)^2 dx)): */
    {a(n)=local(A=1); A=1/(1-serreverse(x-2*x^3/3+x^5/5 +x^2*O(x^n)));n!*polcoeff(A, n)}
    for(n=0,25,print1(a(n),", "))
    
  • PARI
    /* E.g.f. 1 + Series_Reversion(Integral (1+2*x)^2/(1+x)^6 dx): */
    {a(n)=local(A=1); A=1+serreverse( intformal((1+2*x)^2/(1+x +x^2*O(x^n))^6 ));n!*polcoeff(A, n)}
    for(n=0,25,print1(a(n),", "))

Formula

E.g.f. A(x) satisfies: 3 - 15*A(x) + 20*A(x)^2 - (8 - 15*x)*A(x)^5 = 0.
E.g.f.: 1/(1 - Series_Reversion( Integral (1-x^2)^2 dx )).
E.g.f.: 1 + Series_Reversion( Integral (1+2*x)^2/(1+x)^6 dx ).
Recurrence: 4096*(100*n - 341)*a(n) = 30720*(25*n - 83)*a(n-1) + 640*(4500*n^3 - 35595*n^2 + 92875*n - 81419)*a(n-2) - 1800*(1500*n^3 - 13480*n^2 + 40050*n - 39221)*a(n-3) - 81*(5*n - 19)*(5*n - 18)*(5*n - 17)*(5*n - 16)*(100*n - 241)*a(n-4). - Vaclav Kotesovec, Jan 28 2014
a(n) ~ n! * (5/2)^(1/3) * (15/8)^n / (GAMMA(1/3) * n^(2/3)). - Vaclav Kotesovec, Jan 28 2014
Showing 1-3 of 3 results.