Virahāṅka Numbers: 
There is a famous sequence of numbers:
 
\(1\), \(2\), \(3\), \(5\), \(8\), \(13\), \(21\), ... 
 
Each number is obtained by adding preceding two numbers.
 
For example, \(2 + 3 = 5\); \(3 + 5 = 8\).
Origin:
These numbers were first studied in India by Virahāṅka (7th century CE) while exploring poetry rhythms.
 
Later, the Italian mathematician Fibonacci (\(1202 \ CE\)) introduced the same sequence to Europe through his famous book Liber Abaci
  • Rules to remember:
     
    • Start with \(1\) and \(2\).
    • Keep adding the previous two numbers. 
    • \(1\), \(2\), \(3\), \(5\), \(8\), \(13\), \(21\), ...