a(n) = n*a(n-2) + a(n-5) for n >= 5 and with a(0)=0, a(1)=1, a(2)=0, a(3)=3, a(4)=0.

A130637

a(n) = n*a(n-2) + a(n-5) for n >= 5 and with a(0)=0, a(1)=1, a(2)=0, a(3)=3, a(4)=0.

Terms

    a(0) =0a(1) =1a(2) =0a(3) =3a(4) =0a(5) =15a(6) =1a(7) =105a(8) =11a(9) =945a(10) =125a(11) =10396a(12) =1605a(13) =135159a(14) =23415a(15) =2027510a(16) =385036a(17) =34469275a(18) =7065807a(19) =654939640a(20) =143343650a(21) =13754117476a(22) =3188029575a(23) =316351767755a(24) =77167649440

External references