OFFSET
1,2
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (7,0,0,1,-7).
FORMULA
a(n) = 7*a(n-1) + a(n-4) - 7*a(n-5).
From Colin Barker, Dec 24 2015: (Start)
a(n) = 1/200*(25*(-1)^n-(6-8*i)*(-i)^n-(6+8*i)*i^n+37*7^n-50) where i=sqrt(-1).
G.f.: x*(1+2*x+3*x^3) / ((1-x)*(1+x)*(1-7*x)*(1+x^2)).
(End)
MATHEMATICA
Table[FromDigits[PadRight[{}, n, {1, 2, 0, 3}], 7], {n, 30}] (* Harvey P. Dale, May 24 2017 *)
PROG
(PARI) Vec(x*(1+2*x+3*x^3)/((1-x)*(1+x)*(1-7*x)*(1+x^2)) + O(x^30)) \\ Colin Barker, Dec 24 2015
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved