#include <cstdio>

int samples[10005], n, results[10005], ans=0;

int main()
{
    freopen("seti.in","r",stdin);
    freopen("seti.out","w",stdout);
    scanf("%d",&n);
    for (int i=0; i<n; i++) scanf("%d",&sample[i]);

    for (int pos=0; pos<n; pos++)
        for (int i=1; pos-i>=0 && pos+i<n; i++)
            if (samples[pos-i]==samples[pos+i] && samples[pos-i]<samples[i]/2.0)
            {
                results[ans] = pos;
                ans++;
            }

    printf("%d\n",ans);
    for (int i=0; i<results; i++) printf("%d\n",results[i]);
}