A165739 The number of palindromic numbers which are the product of a number and its reversal with 2n-1 digits.

4, 3, 8, 13, 27, 49, 99, 180, 330, 567, 957, 1546, 2479, 3865

Offset

1,1

Comments

Every palindromic numbers which is the product of a number and its reversal has an odd number of digits.

Links

Table of n, a(n) for n=1..14.

Example

a(1)=4 because there are 4 numbers matching the definition with one digit: 0*0=0; 1*1=1; 2*2=4; 3*3=9;
a(2)=3 because there are 3 numbers with three digits: 11*11=121; 12*21=252; 22*22=484;
a(3)=8 because there are 8 numbers with five digits: 101*101=10201; 111*111=12321; 121*121=14641; 102*201=20502; 112*211=23632; 122*221=26962; 202*202=40804; 212*212=44944;

Crossrefs

Cf. A158642.

Sequence in context: A309517 A105185 A357587 * A196132 A198179 A137503

Adjacent sequences: A165736 A165737 A165738 * A165740 A165741 A165742

Keyword

nonn,base

Author

Floris P. van Doorn, Sep 25 2009

Status

approved