A179539 a(0) = 1, a(1) = 0, a(n) = 2*n*(a(n-1) + a(n-2)), n > 1.

1, 0, 4, 24, 224, 2480, 32448, 488992, 8343040, 158976576, 3346392320, 77118115712, 1931148192768, 52214924020480, 1516090021970944, 47049148379742720, 1554087628854837248, 54438650425975718912, 2015738569973900021760, 78666734375195278145536, 3227298917806767126691840

Offset: 0

Author

Gary Detlefs, Jul 18 2010

Keywords

• nonn
• easy

Examples

			a(2)= 4*(0+1)=4, a(3)=6*(4+0)=24, a(4)=8*(24+4)=224...
		

Crossrefs

Cf. A055596.

Formula

D-finite with recurrence: 2*n*a(n-2) + 2*n*a(n - 1) - a(n) = 0. Georg Fischer, Mar 31 2025

Extensions

Definition corrected by Bruno Berselli, Jul 20 2010

Typo in a(7) corrected by Georg Fischer, Mar 31 2025