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A113841
a(n) = a(n-1) + 2^A047240(n) for n>1, a(1)=1.
2
1, 3, 7, 71, 199, 455, 4551, 12743, 29127, 291271, 815559, 1864135, 18641351, 52195783, 119304647, 1193046471, 3340530119, 7635497415, 76354974151, 213793927623, 488671834567, 4886718345671, 13682811367879, 31274997412295
OFFSET
1,2
FORMULA
G.f.: x*(1+2*x+4*x^2)/((-1+x)*(-1+4*x)*(1+4*x+16*x^2)). - Vaclav Kotesovec, Nov 28 2012
a(1)=1, a(2)=3, a(3)=7, a(4)=71, a(n)=a(n-1)+64*a(n-3)-64*a(n-4). - Harvey P. Dale, Nov 18 2013
MATHEMATICA
CoefficientList[Series[(1 + 2 x + 4 x^2) / ((-1 + x) (-1 + 4 x) (1 + 4 x + 16 x^2)), {x, 0, 30}], x] (* Vincenzo Librandi, May 19 2013 *)
LinearRecurrence[{1, 0, 64, -64}, {1, 3, 7, 71}, 30] (* Harvey P. Dale, Nov 18 2013 *)
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Jan 27 2006
EXTENSIONS
Edited with better definition and offset corrected by Omar E. Pol, Jan 08 2009
STATUS
approved