public static long Run(long time)
{
// a[k] = a[k-1] * q
// a[n] = a[m] * q^(n-m)
// S = a[1] * (1 - q^n) / (1 - q)

var S = new Dictionary<long, long>();
var a = new Dictionary<long, long>();

a[1] = 3;

var q = 2;

var n = (long)Math.Ceiling(Math.Log(1 - time * (1 - q) / (double)a[1]) / Math.Log(q));

S[n - 1] = (long)(a[1] * (1 - Math.Pow(2, n - 1)) / (1 - q));
a[n] = a[1] * (long)Math.Pow(q, n - 1);

var remain = time - S[n - 1];
var val = a[n] - remain + 1;

return val;
}