let S1, S2 be sequence of X; ( ( for n being Nat holds S1 . n = (seq1 . n) * (seq2 . n) ) & ( for n being Nat holds S2 . n = (seq1 . n) * (seq2 . n) ) implies S1 = S2 )
assume that
A2:
for n being Nat holds S1 . n = (seq1 . n) * (seq2 . n)
and
A3:
for n being Nat holds S2 . n = (seq1 . n) * (seq2 . n)
; S1 = S2
for n being Element of NAT holds S1 . n = S2 . n
hence
S1 = S2
by FUNCT_2:63; verum