BTC top bottom weekly bands

This indicator is based on the 20 weekly simple moving average and it could be used to help finding potential tops and bottoms on a weekly BTC chart.

When using the provided "coef" parameter set to the default of 0.5 it shows how most bottoms since 2013 have hit the lower band of this indicator.

The lower band is calculated as exp(coef) * sma(close)

Instructions:
- Use with the symbol INDEX:BTCUSD so you can see the price since 2010
- Set the timeframe to weekly
- Use logarithmic chart (toggle "log" on)

Optionals:
- change the coef to 0.6 for a more conservative bottom
- change the coef to 0.4 for a more conservative top