OFFSET
0,2
LINKS
FORMULA
4^n = a(n) + A037576(n) for n >= 1.
a(n) + a(n+1) = A039301(n+2).
a(n) = 4*a(n-1) + a(n-2) - 4*a(n-3). - Harvey P. Dale, Mar 23 2012
G.f.: 1 + x*(3-3*x-4*x^2)/((1-x)*(1+x)*(1-4*x)). - Colin Barker, Aug 28 2012
MATHEMATICA
FromDigits[IntegerDigits[#], 4]&/@(NestList[FromDigits[Flatten[ IntegerDigits[#]/.{3->{2, 1}, 1->{0, 3}}]]&, 1, 30]) (* or *) LinearRecurrence[{4, 1, -4}, {1, 3, 9}, 31](* Harvey P. Dale, Mar 23 2012 *)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Creighton Dement, Mar 01 2005
EXTENSIONS
More terms from Harvey P. Dale, Mar 23 2012
STATUS
approved