OFFSET
0,2
COMMENTS
Add 1, triple, add 1, triple, ... (of course this is simply a restatement of one of Philippe Deléham's formulas). - Jon Perry, Aug 11 2014
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,4,0,-3).
FORMULA
a(n)=4a(n-2)-3a(n-4); a(n)=3*3^(n/2)(1/4+sqrt(3)/4+(1/4-sqrt(3)/4)(-1)^n)+(-1)^n/2-1.
a(n) = a(n-1)*3 if n odd; a(n) = a(n-1)+1 if n even. - Philippe Deléham, Apr 22 2013
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Apr 22 2004
STATUS
approved