Help:=proc(): print(`JC(w), YN(INI,n), JC1(w) `): end:

#The Conway Look-And-Say sequence

#JC(w): inputs any list in  and outputs its
#Yusra transform
#a1^c1,a2^c2,..., ar^cr ->[a1,c1,a2,c2,a3,c3, ...]
JC:=proc(w) local i,a1,c1,w1,J1:
option remember:

if w=[] then
 RETURN([]):
fi:


a1:=w[1]:

for i from 1 to nops(w) while w[i]=a1 do od:

c1:=i-1:

w1:=w[c1+1..nops(w)]:

J1:=JC(w1):

[c1,a1,op(J1)]:



end:


#YN(INI,n): the first n terms of the
#sequence : "length of JC^n(INI)
YN:=proc(INI,n) local s,i,Cu:

s:=[]:

Cu:=INI:

for i from 1 to n do
 s:=[op(s), nops(Cu)]:
 Cu:=JC(Cu):
od:

s:

end: 


#JC1(w): inputs any list in  and outputs its
#Yusra transform, not using recursion
#a1^c1,a2^c2,..., ar^cr ->[a1,c1,a2,c2,a3,c3, ...]
JC1:=proc(w) local i,a1,c1,w1,J1,L:
option remember:

if w=[] then
 RETURN([]):
fi:

L:=[]:

w1:=w:

while w1<>[] do

a1:=w1[1]:

for i from 1 to nops(w1) while w1[i]=a1 do od:

c1:=i-1:

L:=[op(L),c1,a1]:

w1:=w1[c1+1..nops(w1)]:

od:
L:

end:



#YN1(INI,n): the first n terms of the
#sequence : "length of JC^n(INI)
YN1:=proc(INI,n) local s,i,Cu:

s:=[]:

Cu:=INI:

for i from 1 to n do
 s:=[op(s), nops(Cu)]:
 Cu:=JC1(Cu):
od:

s:

end: