OFFSET
1,1
COMMENTS
a(n) is also the irregularity strength of the (n-1)-Cameron graph. - Eric W. Weisstein, Sep 02 2025
LINKS
Eric Weisstein's World of Mathematics, Cameron Graph.
Eric Weisstein's World of Mathematics, Irregularity Strength.
Index entries for linear recurrences with constant coefficients, signature (1,0,1,-1).
FORMULA
a(n) = floor((8*n-2)/3). - Gary Detlefs, Mar 13 2010
From Wesley Ivan Hurt, Jun 09 2016: (Start)
G.f.: x*(2+2*x+3*x^2+x^3)/((x-1)^2*(1+x+x^2)).
a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.
a(n) = (24*n-9+2*sqrt(3)*sin(2*n*Pi/3))/9.
a(3k) = 8k-1, a(3k-1) = 8k-4, a(3k-2) = 8k-6. (End)
MAPLE
seq(floor((8*n-3)/3), n=1..51); # Gary Detlefs, Mar 07 2010
MATHEMATICA
Table[Floor[(8 n - 2)/3], {n, 50}] (* Wesley Ivan Hurt, Feb 15 2014 *)
LinearRecurrence[{1, 0, 1, -1}, {2, 4, 7, 10}, 80] (* Harvey P. Dale, Feb 02 2025 *)
Table[(24 n - 9 + 2 Sqrt[3] Sin[2 n Pi/3])/9, {n, 20}] (* Eric W. Weisstein, Sep 02 2025 *)
CoefficientList[Series[(2 + 2 x + 3 x^2 + x^3)/((-1 + x)^2 (1 + x + x^2)), {x, 0, 20}], x] (* Eric W. Weisstein, Sep 02 2025 *)
PROG
(Magma) [n : n in [0..150] | n mod 8 in [2, 4, 7]]; // Wesley Ivan Hurt, Jun 09 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved
