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A096965 Number of sets of even number of even lists, cf. A000262. 1
1, 1, 7, 37, 241, 2101, 18271, 201097, 2270017, 29668681, 410815351, 6238931821, 101560835377, 1765092183037, 32838929702671, 644215775792401, 13441862819232001, 293976795292186897, 6788407001443004647 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..200

FORMULA

E.g.f.: exp(x/(1-x^2))*cosh(x^2/(1-x^2)).

a(n) = (n!*sum(m=floor((n+1)/2)..n, (binomial(n-1,2*m-n-1))/(2*m-n)!)). [ Vladimir Kruchinin, Mar 10 2013]

Recurrence: (n-2)*a(n) = (2*n-3)*a(n-1) + (n-1)*(2*n^2 - 8*n + 7)*a(n-2) + (n-2)*(n-1)*(2*n-5)*a(n-3) - (n-4)*(n-3)*(n-2)^2*(n-1)*a(n-4). - Vaclav Kotesovec, Sep 29 2013

a(n) ~ exp(2*sqrt(n)-n-1/2)*n^(n-1/4)/(2*sqrt(2)) * (1-5/(48*sqrt(n))). - Vaclav Kotesovec, Sep 29 2013

MATHEMATICA

Drop[ Range[0, 20]! CoefficientList[ Series[ Exp[(x/(1 - x^2))]Cosh[x^2/(1 - x^2)], {x, 0, 20}], x], 1] (* Robert G. Wilson v, Aug 19 2004 *)

CROSSREFS

Cf. A088026, A088009.

Sequence in context: A039938 A285846 A102760 * A159597 A217723 A100309

Adjacent sequences:  A096962 A096963 A096964 * A096966 A096967 A096968

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, Aug 18 2004

EXTENSIONS

More terms from Robert G. Wilson v, Aug 19 2004

STATUS

approved

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Last modified January 29 14:23 EST 2020. Contains 331338 sequences. (Running on oeis4.)