Legion's number of the first kind

Legion's number of the first kind is equal to 666⁶⁶⁶.

Notation	Approximation
BLN	$Z(Z)AAA_{666}$
Hyper-B Notation (V4)	B(666,2,2)
Hpyer-B Notation (V5)	$B[[[[[666]2]]]]$
Blank hierarchy	$B_4(666)$
Arrow notation	$666\uparrow\uparrow2$
BEAF	{666,2,2}
Steinhaus-Moser Notation	666[3]
Hyper-E notation	E[666]1#2
Strong array notation	s(666,2,2)
Slow-growing hierarchy	$g_{\omega^{\omega}}(666)$