OFFSET
0,6
COMMENTS
This sequence has the form (0+2k,0+2k,1+2k,0+2k,1+2k,2+2k,1+2k) for k>=0.
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,1,-1).
FORMULA
From Colin Barker, Jul 02 2017: (Start)
G.f.: x^2*(1 + x)*(1 - x + x^2)^2 / ((1 - x)^2*(1 + x + x^2 + x^3 + x^4 + x^5 + x^6)).
a(n) = a(n-1) + a(n-7) - a(n-8) for n>7.
(End)
MATHEMATICA
Table[Count[Mod[Table[2 ((n - 1)^2 + k) - 1, {k, 1, 2 n - 1}], 7],
0], {n, 0, 100}]
PROG
(PARI) concat(vector(2), Vec(x^2*(1 + x)*(1 - x + x^2)^2 / ((1 - x)^2*(1 + x + x^2 + x^3 + x^4 + x^5 + x^6)) + O(x^100))) \\ Colin Barker, Jul 02 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ralf Steiner, Jun 25 2017
STATUS
approved