<Dd> 1, 11, 21, 1211, 111221, 312211, 13112221, 1113213211,...(sequence A005150 in the OEIS). </Dd> <P> To generate a member of the sequence from the previous member, read off the digits of the previous member, counting the number of digits in groups of the same digit . For example: </P> <Ul> <Li> 1 is read off as "one 1" or 11 . </Li> <Li> 11 is read off as "two 1s" or 21 . </Li> <Li> 21 is read off as "one 2, then one 1" or 1211 . </Li> <Li> 1211 is read off as "one 1, one 2, then two 1s" or 111221 . </Li> <Li> 111221 is read off as "three 1s, two 2s, then one 1" or 312211 . </Li> </Ul> <Li> 1 is read off as "one 1" or 11 . </Li>

When do we look at number 2 but say 10