A334888 a(n) = Sum_{k >= 0} f(d_k) * 3^k where Sum_{k >= 0} d_k * 8^k is the base 8 representation of n and f(k) = 0, 1, 2, 2, 2, 1, 0, 0 for k = 0..7, respectively.
0, 1, 2, 2, 2, 1, 0, 0, 3, 4, 5, 5, 5, 4, 3, 3, 6, 7, 8, 8, 8, 7, 6, 6, 6, 7, 8, 8, 8, 7, 6, 6, 6, 7, 8, 8, 8, 7, 6, 6, 3, 4, 5, 5, 5, 4, 3, 3, 0, 1, 2, 2, 2, 1, 0, 0, 0, 1, 2, 2, 2, 1, 0, 0, 9, 10, 11, 11, 11, 10, 9, 9, 12, 13, 14, 14, 14, 13, 12, 12, 15, 16
Offset: 0
Examples
For n = 42: - 42 = 5*8^1 + 2*8^0, - so a(42) = f(5)*3^1 + f(2)*3^0 = 1*3^1 + 2*3^0 = 5.
Links
- Rémy Sigrist, Table of n, a(n) for n = 0..4095 (n = 0..8^4-1)
- Rémy Sigrist, Colored scatterplot of (a(n), A334889(n)) for n = 0..8^6-1 (where the hue is function of n)
- Wikipedia, Sierpinski carpet
Programs
-
PARI
a(n) = { my (f=[0, 1, 2, 2, 2, 1, 0, 0], d=Vecrev(digits(n, #f))); sum(k=0, #d-1, f[1+d[1+k]] * 3^k) }
Comments