Lychrel number

A Lychrel number is a natural number which cannot form a palindrome through the iterative process of repeatedly reversing its base 10 digits and adding the resulting numbers.

see: wikipedia:Lychrel number for details

Similar examples

Kaprekar's constant

see: wikipedia:6174 (number) for details.

Divide by 9

Palindromic number occurs by the division of nine after subtracting the reverse of a number.

• Example:

(5463 - 3645)/9 = 202 <- palindrome

Other

Divide any number by 7 and notice the pattern 14-28-57 repeated. The start of the sequence 14... occurs with the following pattern 1489657. The following is for 7 - 21:

1.00000000000000000000
1.14285714285714285714
1.28571428571428571428
1.42857142857142857142
1.57142857142857142857
1.71428571428571428571
1.85714285714285714285
2.00000000000000000000
2.14285714285714285714
2.28571428571428571428
2.42857142857142857142
2.57142857142857142857
2.71428571428571428571
2.85714285714285714285
3.00000000000000000000

1489657/7 = 212808.14285714285714285714
1+4+8+9+6+5+7 = 40

External links

• wikipedia:Palindromic number
• wikipedia:196 (number)
• 229 primes