Lambda the Ultimate

member[x; y] = [null[y]→F;
                equal[x; car[y]]→T;
                T→member[x; cdr[y]]]

M-expression definition of member from the LISP 1.5 Programmer's Manual, 1962.

REAL FUNCTION SUMSQUARE(X(I));
  BEGIN INTEGER J; REAL Y;
    FOR J ← l STEP 1 UNTIL > I DO
      y ← Y + X(J)^2;
  RETURN Y
END

LISP 2 from "The LISP 2 Programming Language and System" by Paul W. Abrahams et al, 1966.

LISP PROCEDURE FACTORIAL N;
  IF N <= 1 THEN 1
   ELSE N * FACTORIAL (N-1);

RLISP factorial from The Portable Standard LISP User's Manual, Version 3, 1982.