A158642 Palindromic numbers which are the product of a number k and its reversal (k written backwards).

0, 1, 4, 9, 121, 252, 484, 10201, 12321, 14641, 20502, 23632, 26962, 40804, 44944, 1002001, 1113111, 1226221, 1234321, 1357531, 2005002, 2126212, 2216122, 2249422, 2347432, 2429242, 4008004, 4229224, 100020001, 102030201, 104060401, 110131011, 112242211, 114373411, 120262021

Offset: 0

Author

Paolo P. Lava and Giorgio Balzarotti, Mar 23 2009

Keywords

• nonn
• easy
• base
• changed

Comments

Apart from 3 which produces 9 (3*3), all the other numbers k which satisfy the definition are formed by digits 0, 1 and 2 only. Subset of A002113.

Every term has an odd number of digits. - Floris P. van Doorn, Sep 25 2009

Examples

			0*0=0; 1*1=1; 2*2=4; 3*3=9; 11*11=121; 12*21=252; 22*22=484; 101*101=10201; 102*201=20502; etc.
		

Links

• Floris P. van Doorn, Table of n, a(n) for n=0..10126 (terms < 10^27).

Crossrefs

Cf. A002113.

Extensions

Corrected by Floris P. van Doorn, Sep 25 2009