OFFSET
0,3
COMMENTS
Permutation of nonnegative numbers.
LINKS
FORMULA
a(n) = 2*a(n-9) - a(n-18) for n >= 18.
a(9*n) = 12*n, a(9*n+1) = 8*n+1, a(9*n+2) = 8*n+3, a(9*n+3) = 12*n+4, a(9*n+4) = 8*n+2, a(9*n+5) = 8*n+5, a(9*n+6) = 12*n+8, a(9*n+7) = 8n+7, a(9*n+8) = 8*n+6.
a(n) = a(n-3) + a(n-9) - a(n-12) for n >= 12.
G.f.: (x + 3*x^2 + 4*x^3 + x^4 + 2*x^5 + 4*x^6 + 5*x^7 + x^8 + 4*x^9 + x^10 + 2*x^11) / ((1 - x)^2*(1 + x + x^2)^2*(1 + x^3 + x^6)).
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Nov 25 2023
STATUS
approved