TOPICS
A Banach space 
is called prime if each infinite-dimensional complemented
subspace of 
is isomorphic to 
(Lindenstrauss and Tzafriri 1977).
Pełczyński (1960) proved that 
(the Banach space
of all complex sequences converging to zero together with the supremum
norm) and 
for 
(the space of all complex sequences 
such that 
) are prime. The L-infinity-space 
of all bounded complex sequences
is also prime (Lindenstrauss 1967).
This entry contributed by Mohammad Sal Moslehian
." Israel J. Math. 5,
153-156, 1967.Lindenstrauss, J. and Tzafriri, L. Classical
Banach Spaces. I. Sequence Spaces. New York: Springer-Verlag, 1977.Pełczyński,
A. "Projections in Certain Banach Spaces." Studia Math. 19,
209-228, 1960.Moslehian, Mohammad Sal. "Prime Banach Space." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/PrimeBanachSpace.html