A130637 - OEIS

%I #23 Sep 08 2022 08:45:30

%S 0,1,0,3,0,15,1,105,11,945,125,10396,1605,135159,23415,2027510,385036,

%T 34469275,7065807,654939640,143343650,13754117476,3188029575,

%U 316351767755,77167649440,7908937537525,2020113002916,213544501542750,56879515849403,6192867712389190

%N 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.

%F a(n) = n*a(n-2) + a(n-5) for n >= 5. - _Jianing Song_, Oct 10 2018

%t RecurrenceTable[{a[0] == 0, a[1] == 1, a[2] == 0, a[3] == 3, a[4] == 0, a[n] == n a[n - 2] + a[n - 5]}, a, {n, 0, 30}] (* _Bruno Berselli_, Oct 11 2018 *)

%o (PARI) a(n) = if(n<5, (n==1) + 3*(n==3), n*a(n-2) + a(n-5)) \\ _Jianing Song_, Oct 10 2018

%o (Magma) I:=[0,1,0,3,0]; [n le 5 select I[n]  else (n-1)*Self(n-2)+Self(n-5): n in [1..30]]; // _Vincenzo Librandi_, Oct 11 2018

%K nonn,easy

%O 0,4

%A _Roger L. Bagula_, Jun 19 2007

%E Edited, new name, and offset corrected by _Jianing Song_, Oct 10 2018