A symmetrical number which is written in some base as . The first few are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 111, 121, ... (Sloane's A002113).

The first few for which the Pronic Number is palindromic are 1, 2, 16, 77, 538, 1621, ... (Sloane's A028336), and the first few palindromic numbers which are Pronic are 2, 6, 272, 6006, 289982, ... (Sloane's A028337). The first few numbers whose squares are palindromic are 1, 2, 3, 11, 22, 26, ... (Sloane's A002778), and the first few palindromic squares are 1, 4, 9, 121, 484, 676, ... (Sloane's A002779).

**References**

De Geest, P. ``Palindromic Products of Two Consecutive Integers.'' http://www.ping.be/~ping6758/consec.htm.

De Geest, P. ``Palindromic Squares.'' http://www.ping.be/~ping6758/square.htm.

Pappas, T. ``Numerical Palindromes.'' *The Joy of Mathematics.* San Carlos, CA: Wide World Publ./Tetra, p. 146, 1989.

Sloane, N. J. A. A028336, A028337 A002113/M0484, A002778/M0907, and A002779/M3371 in ``An On-Line Version of the Encyclopedia of Integer Sequences.'' http://www.research.att.com/~njas/sequences/eisonline.html.

© 1996-9

1999-05-26