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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A348607 Decimal expansion of BesselJ(1,2).

Original entry on oeis.org

5, 7, 6, 7, 2, 4, 8, 0, 7, 7, 5, 6, 8, 7, 3, 3, 8, 7, 2, 0, 2, 4, 4, 8, 2, 4, 2, 2, 6, 9, 1, 3, 7, 0, 8, 6, 9, 2, 0, 3, 0, 2, 6, 8, 9, 7, 1, 9, 6, 7, 5, 4, 4, 0, 1, 2, 1, 1, 3, 9, 0, 2, 0, 7, 6, 4, 0, 8, 7, 1, 1, 6, 2, 8, 9, 6, 1, 2, 1, 8, 4, 9, 4, 8, 3, 9, 9
Offset: 0

Views

Author

Dumitru Damian, Oct 25 2021

Keywords

Examples

			0.5767248077568733872...
		

Crossrefs

Bessel function values: A334380 (J(0,1)), A091681 (J(0,2)), A334383 (J(0,sqrt(2))), this sequence (J(1,2)), A197036 (I(0,1)), A070910 (I(0,2)), A334381 (I(0,sqrt(2))), A096789 (I(1,2)).

Programs

  • Mathematica
    RealDigits[BesselJ[1, 2], 10, 100][[1]] (* Amiram Eldar, Oct 25 2021 *)
  • PARI
    besselj(1, 2) \\ Michel Marcus, Oct 25 2021
  • Sage
    bessel_J(1, 2).n(digits=100)
    

Formula

Equals Sum_{k>=0} (-1)^k/(k!*(k+1)!).

A245119 G.f. satisfies: A(x) = 1 + x^2 + x^2*A'(x)/A(x).

Original entry on oeis.org

1, 0, 1, 2, 6, 22, 100, 554, 3654, 28014, 244572, 2392042, 25877610, 306553246, 3944541224, 54764396346, 815786104186, 12976263731454, 219490418886728, 3933636232278866, 74453982353188846, 1484056255756797222, 31071499784792496588, 681729867750992165514, 15641641334118250802462
Offset: 0

Views

Author

Paul D. Hanna, Jul 24 2014

Keywords

Examples

			G.f.: A(x) = 1 + x^2 + 2*x^3 + 6*x^4 + 22*x^5 + 100*x^6 + 554*x^7 + 3654*x^8 +...
where the logarithmic derivative equals (A(x) - 1 - x^2)/x^2:
A'(x)/A(x) = 2*x + 6*x^2 + 22*x^3 + 100*x^4 + 554*x^5 + 3654*x^6 +...+ a(n+2)*x^n +...
thus the logarithm begins:
log(A(x)) = 2*x^2/2 + 6*x^3/3 + 22*x^4/4 + 100*x^5/5 + 554*x^6/6 + 3654*x^7/7 +...+ a(n+1)*x^n/n +...
		

References

  • Compare g.f. to: G(x) = 1 + x + x^2*G'(x)/G(x) when G(x) = 1/(1-x).

Crossrefs

Cf. A245308.

Programs

  • PARI
    {a(n)=local(A=1+x^2);for(i=1,n,A = 1 + x^2 + x^2*A'/(A +x*O(x^n)));polcoeff(A,n)}
    for(n=0,30,print1(a(n),", "))
    
  • PARI
    /* From A(x) = exp(-x)*G(x), where G(x) = e.g.f. of A245308: */
    {a(n)=local(G=1+x);for(i=1,n,G = exp(x +x*O(x^n))*(1 + x^2*G'/(G +x*O(x^n))));
    polcoeff(exp(-x +x*O(x^n))*G,n)}
    for(n=0,30,print1(a(n),", "))

Formula

G.f. A(x) satisfies:
(1) A(x) = exp(-x)*G(x) where G(x) = exp(x)*(1 + x^2*G'(x)/G(x)) is the e.g.f. of A245308.
(2) A(x) = exp( Integral (A(x) - 1 - x^2)/x^2 dx ).
a(n) ~ BesselJ(1,2) * (n-1)!. - Vaclav Kotesovec, Jul 25 2014
Showing 1-2 of 2 results.