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A267711
Numbers k such that k mod 3 = k mod 5.
2
0, 1, 2, 15, 16, 17, 30, 31, 32, 45, 46, 47, 60, 61, 62, 75, 76, 77, 90, 91, 92, 105, 106, 107, 120, 121, 122, 135, 136, 137, 150, 151, 152, 165, 166, 167, 180, 181, 182, 195, 196, 197, 210, 211, 212, 225, 226, 227, 240, 241, 242, 255, 256, 257, 270, 271, 272, 285, 286
OFFSET
1,3
COMMENTS
Periodic differences between the consecutive terms (1,1,13,1,1,13,1,1,13,1,1...).
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
Cf. A267540.
Sequence in context: A322149 A163480 A037312 * A108472 A039771 A032934
KEYWORD
nonn,easy
AUTHOR
Mikk Heidemaa, Jan 19 2016
STATUS
approved