OFFSET
0,1
LINKS
FORMULA
a(n) = 1 + abs(n - 2 - 6*round((2n - 3)/6)) for n > 3.
G.f.: (3-x-x^2-x^3+5*x^4-x^5+2*x^6)/(1-x-x^6+x^7). - Robert Israel, Dec 13 2016
Sum_{n>=0, n!=3} (-1)^n/a(n) = log(2) (A002162). - Amiram Eldar, Dec 25 2023
MAPLE
f:= gfun:-rectoproc({a(n+7)-a(n+6)-a(n+1)+a(n)=0, seq(a(i)=[3, 2, 1, 0, 5, 4, 9][i+1], i=0..6)}, a(n), remember):
map(f, [$0..100]); # Robert Israel, Dec 13 2016
MATHEMATICA
Reverse/@TakeDrop[#, 4]&/@Partition[Range[0, 80], 6]//Flatten (* Requires Mathematica version 10 or later *) (* or *) LinearRecurrence[ {1, 0, 0, 0, 0, 1, -1}, {3, 2, 1, 0, 5, 4, 9}, 80] (* Harvey P. Dale, Dec 16 2017 *)
PROG
(Magma) &cat[[6*k+3, 6*k+2, 6*k+1, 6*k, 6*k+5, 6*k+4] : k in [0..20]];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Dec 09 2016
STATUS
approved