OFFSET
1,3
COMMENTS
Periodic differences between the consecutive terms (1,1,13,1,1,13,1,1,13,1,1...).
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,1,-1).
FORMULA
a(n) = (1/3)*(15*n - 12*cos((2*Pi*n)/3) + 4*sqrt(3)*sin((2*Pi*n)/3) - 27).
G.f.: x^2*(13*x^2+x+1) / ((x-1)^2*(x^2+x+1)).
a(n) = a(n-1) + a(n-3) - a(n-4) for n > 4. - Colin Barker, Jan 28 2016
MATHEMATICA
Select[ Range[0, 10000], (Mod[#, 3] == Mod[#, 5]) &]
PROG
(PARI) lista(nn) = for(n=0, nn, if(n%3 == n%5, print1(n, ", "))); \\ Altug Alkan, Jan 19 2016
(PARI) concat(0, Vec(x^2*(1+x+13*x^2)/((1-x)^2*(1+x+x^2)) + O(x^100))) \\ Colin Barker, Jan 28 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mikk Heidemaa, Jan 19 2016
STATUS
approved