A palindrome is usually a word (or sentence) which reads the same whether read forwards or backwards: for example "Madam, I'm Adam" (or her reply: "Eve").
We can also have palindromic numbers, such as 121, or 14641.
The prime numbers always provide a rich field for research. There are palindromic primes in base ten, and in bases other than ten, and some of these palindromic primes are palindromic in more than one base.

A good example (the most prolific so far) is 373; it has the forms 565 in base eight; 11311 in base four, and 454 in base nine. (I haven't checked 373 in bases above base ten yet)

(232 = 151 base six)(414=131 base nine)

Here is a list of results so far
Base
Three	111, 212 (111 is also 11 base twelve)
Four	101, 131, 323
Five	111,131, 232, 313, 414
Six	11, 101, 111, 141, 151, 515, 525
	(515 is 191 base ten, and 232 base nine)
Seven	131, 212, 313, 515, 535, 616
	(313 = 111 twelve) (515 = 10001 base four)
Eight	111,131,141,161,323,343, 373, 535, 565, 717, 737, 747, 767
	(343 = 272 base nine)
Nine	131,151, 212, 232, 272, 414, 454, 515, 737, 757, 838, 858, 878
	(858 = 10301 base five) (232 = 191 base ten)
	(454 is 373 base ten) (212 = 20102 base three)