OFFSET
1,1
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,0,2,0,0,-1).
FORMULA
a(3*n+1) = 7*n+2 = A017005(n), a(3*n+2) = 2*n+13, a(3*n+3) = 21*n+20.
From Chai Wah Wu, Sep 24 2020: (Start)
a(n) = 2*a(n-3) - a(n-6) for n > 6.
G.f.: x*(x^5 + 8*x^4 + 5*x^3 + 20*x^2 + 13*x + 2)/(x^6 - 2*x^3 + 1). (End)
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Zak Seidov, May 02 2005
STATUS
approved