A241543 - OEIS

%I #8 Jul 17 2016 07:15:20

%S 1,1,2,2,2,6,4,20,10,70,28,252,84,924,264,3432,858,12870,2860,48620,

%T 9724,184756,33592,705432,117572,2704156,416024,10400600,1485800,

%U 40116600,5348880,155117520,19389690,601080390,70715340,2333606220,259289580,9075135300

%N a(n) = A241477(n, n).

%C See A241477 and A232500 for the combinatorial definitions.

%F a(n) = 2*floor(n/2)*(n-2)!/floor(n/2)!^2 for n>=2.

%F a(n+2) = 2*A057977(n) for n>=0. - _Peter Luschny_, Jul 17 2016

%p A241543 := proc(n)

%p     if n < 2 then 1

%p   else 2*iquo(n,2)*(n-2)!/iquo(n,2)!^2

%p     fi end:

%p seq(A241543(n), n=0..37);

%Y Cf. A057977, A241477, A232500.

%K nonn

%O 0,3

%A _Peter Luschny_, Apr 25 2014