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A245119 G.f. satisfies: A(x) = 1 + x^2 + x^2*A'(x)/A(x). 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

REFERENCES

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

LINKS

Paul D. Hanna, Table of n, a(n) for n = 0..300

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

EXAMPLE

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 +...

PROG

(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), ", "))

CROSSREFS

Cf. A245308.

Sequence in context: A088819 A177478 A052517 * A012270 A009585 A012267

Adjacent sequences:  A245116 A245117 A245118 * A245120 A245121 A245122

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 24 2014

STATUS

approved

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Last modified April 22 07:26 EDT 2021. Contains 343163 sequences. (Running on oeis4.)