A093146 Third binomial transform of Pell(3n-1).

1, 5, 50, 750, 12500, 212500, 3625000, 61875000, 1056250000, 18031250000, 307812500000, 5254687500000, 89703125000000, 1531328125000000, 26141406250000000, 446261718750000000, 7618164062500000000

Offset: 0

Author

Paul Barry, Mar 26 2004

Keywords

• easy
• nonn

Links

• Index entries for linear recurrences with constant coefficients, signature (20,-50).

Crossrefs

Cf. A000129, A093144, A093147.

Formula

G.f.: (1-15*x)/(1 - 20*x + 50*x^2);

a(n) = (10 + 5*sqrt(2))^n*(1/2 - sqrt(2)/4) + (10 - 5*sqrt(2))^n*(1/2 + sqrt(2)/4).