#self doubt

Question

Can someone please verify it ? isn't should be 8. 

https://www.toppr.com/ask/question/the-cardinality-of-the-power-set-of-left-phi-left-phiright-left-phi-left/

Let $S=\{\varphi ,\left\{\varphi \right\},\{\varphi ,\left\{\varphi \right\}\}\}$
$P\left(s\right)=$ Power Set of set $S$
$P\left(s\right)=\{\varphi ,\left\{\varphi \right\},\{\varphi ,\left\{\varphi \right\}\},\{\varphi ,\{\varphi ,\left\{\varphi \right\}\}\},\{\left\{\varphi \right\},\{\varphi ,\left\{\varphi \right\}\}\},\{\varphi ,\left\{\varphi \right\},\{\varphi ,\left\{\varphi \right\}\}\}\}$
$n\left(P\right(s\left)\right)=6$.