Cryptography

• Mathematical Ciphers: from Caesar to RSA, American Mathematical Society, Mathematical World Series, Vol 25, 2006.

Ducci Sequences (aka n-number game)

• "Even Ducci-Sequences," Fibonacci Quarterly, 37(1999), 145-153.
• "Ducci processes of 5-tuples," Fibonacci Quarterly, 36(1998), 419-434.
• "Length of n-number game," Fibonacci Quarterly, 28(1990), 259-265.
• "Length of 7-number game," Fibonacci Quarterly, 26(1988), 195-204.
• "The cycles of differences of integers," J. of Number Theory, 13(1981), 255-261.

Kaprekar Routine (and variations on it)

• "The Switch, Subtract, Reorder Routine," Fibonacci Quarterly, 33(1995), 432-440.
• "A Variation on the Two-Digit Kaprekar Routine," Fibonacci Quarterly, 31(1993), 138-145.
• "The determination of all decadic Kaprekar constants," (with G. D. Prichett and J. F. Lapenta), Fibonacci Quarterly, 19(1981), 45-52.
• "An algorithm to determine self-producing r-digit g-adic integers," (with G. D. Prichett and J. F. Lapenta), J. Reine Agnew. Math. 310(1979), 100-110.
• "A bound on Kaprekar constants," J. Reine Agnew. Math. 310(1979), 196-203.

Other

• "Trees for k-reverse multiples," Fibonacci Quarterly, 30(1992), 166-174.
• "k-reverse multiples," Fibonacci Quarterly, 30(1992), 126-132.
• "Generalized transposable integers," Fibonacci Quarterly, 26(1988), 58-63.
• "Transposable integers in arbitrary bases," Fibonacci Quarterly, 25(1987), 263-267.
• "A counterexample to two conjectures about high order derivatives and regularity," Osaka J. Math. 14(1977), 159-163.

Teaching Related Papers

• "Discovering the derivative of an exponential function," PRIMUS, Vol VII, No. 1, March 1997, 18-24.
• "Two Familiar Calculus Theorems: Modified so their proofs are comprehensible to first semester students," PRIMUS, Vol VI, No. 2, June 1996, 107-116.
• "Using a Graphing Calculator to Estimate Errors in the Trapezoidal Rule," PRIMUS, Vol V, No. 1, March 1995, 33-36.