A093147 Third binomial transform of Pell(3n+1).
1, 15, 250, 4250, 72500, 1237500, 21125000, 360625000, 6156250000, 105093750000, 1794062500000, 30626562500000, 522828125000000, 8925234375000000, 152363281250000000, 2601003906250000000, 44401914062500000000
Offset: 0
Links
- Index entries for linear recurrences with constant coefficients, signature (20,-50).
Formula
G.f.: (1-5*x)/(1 - 20*x + 50*x^2);
a(n) = ((1 + sqrt(2))*(10 + 5*sqrt(2))^n - (1 - sqrt(2))*(10-5*sqrt(2))^n)/(2*sqrt(2)).