A184942 E.g.f.: 1/( cos(log(1-x)) + sin(log(1-x)) ).

1, 1, 4, 22, 162, 1490, 16440, 211580, 3111620, 51477860, 946225200, 19131604600, 421979473800, 10083011777800, 259461056701600, 7153463299918000, 210372376616298000, 6573394764766154000, 217477401066324360000, 7594856249571370364000, 279190943147187411860000

Offset

0,3

Comments

Compare e.g.f. to 1/(cosh(log(1-x)) + sinh(log(1-x))) = 1/(1-x).

Links

Table of n, a(n) for n=0..20.

Formula

a(n) ~ n! /(sqrt(2)*exp(Pi/4)*(1-exp(-Pi/4))^(n+1)). - Vaclav Kotesovec, Oct 18 2013

Example

E.g.f.: A(x) = 1 + x + 4*x^2/2! + 22*x^3/3! + 162*x^4/4! + 1490*x^5/5! +...
where 1/A(1-exp(x)) = cos(x) + sin(x).

Mathematica

CoefficientList[Series[1/(Cos[Log[1-x]] + Sin[Log[1-x]]), {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Oct 18 2013 *)

Prog

(PARI) {a(n)=n!*polcoeff(1/(cos(log(1-x+x*O(x^n)))+sin(log(1-x+x*O(x^n)))), n)}

Crossrefs

Sequence in context: A087547 A218678 A346968 * A000779 A053144 A089464

Adjacent sequences: A184939 A184940 A184941 * A184943 A184944 A184945

Keyword

nonn

Author

Paul D. Hanna, Dec 21 2011

Status

approved