:: deftheorem defines fAP-like NUMBER06:def 3 :
for f being real-valued FinSequence holds
( f is fAP-like iff for i being Nat st i in dom f & i + 1 in dom f & i + 2 in dom f holds
(f . (i + 2)) - (f . (i + 1)) = (f . (i + 1)) - (f . i) );