login
A249222
Expansion of x*(1+5*x-5*x^3)/(1-6*x^2+5*x^4).
2
1, 5, 6, 25, 31, 125, 156, 625, 781, 3125, 3906, 15625, 19531, 78125, 97656, 390625, 488281, 1953125, 2441406, 9765625, 12207031, 48828125, 61035156, 244140625, 305175781, 1220703125, 1525878906, 6103515625, 7629394531, 30517578125, 38146972656, 152587890625
OFFSET
1,2
FORMULA
a(n) = 6*a(n-2)-5*a(n-4).
MATHEMATICA
CoefficientList[Series[(1 + 5 x - 5 x^3)/(1 - 6 x^2 + 5 x^4), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 23 2014 *)
PROG
(PARI) Vec((1+5*x-5*x^3)/(1-6*x^2+5*x^4) + O(x^100))
(PARI) a(n)=round((9-(-1)^n)*5^(n\2)/8) \\ Tani Akinari, Oct 26 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Oct 23 2014
STATUS
approved