0,2

The initial terms coincide with those of A003947, although the two sequences are eventually different.

First disagreement at index 25: a(25) = 1407374883553270, A003947(25) = 1407374883553280. - Klaus Brockhaus, Apr 25 2011

Computed with Magma using commands similar to those used to compute A154638.

Index entries for linear recurrences with constant coefficients, signature (3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, -6).

G.f.: (t^25 + 2*t^24 + 2*t^23 + 2*t^22 + 2*t^21 + 2*t^20 + 2*t^19 + 2*t^18 + 2*t^17 + 2*t^16 + 2*t^15 + 2*t^14 + 2*t^13 + 2*t^12 + 2*t^11 + 2*t^10 + 2*t^9 + 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(6*t^25 - 3*t^24 - 3*t^23 - 3*t^22 - 3*t^21 - 3*t^20 - 3*t^19 - 3*t^18 - 3*t^17 - 3*t^16 - 3*t^15 - 3*t^14 - 3*t^13 - 3*t^12 - 3*t^11 - 3*t^10 - 3*t^9 - 3*t^8 - 3*t^7 - 3*t^6 - 3*t^5 - 3*t^4 - 3*t^3 - 3*t^2 - 3*t + 1).

With[{num=Total[2t^Range[24]]+t^25+1, den=Total[-3 t^Range[24]]+ 6t^25+ 1}, CoefficientList[Series[num/den, {t, 0, 30}], t]] (* Harvey P. Dale, Dec 18 2012 *)

Cf. A003947 (G.f.: (1+x)/(1-4*x)).

Sequence in context: A168922 A168970 A169018 * A169114 A169162 A169210

Adjacent sequences: A169063 A169064 A169065 * A169067 A169068 A169069

John Cannon and N. J. A. Sloane, Dec 03 2009

approved