Beach Day by Rodger Bliss
May 2024

Yet One More Sequence

Riddle: What is the next number in this sequence?
3, 13, 1113, 3113

Thanks Brent for your riddle submission!

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6 guesses to Yet One More Sequence

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  • That’s not it, keep trying Acary.

  • That is not it either mshaw. Keep trying!

  • anant

    132113. (isn’t this called the conway sequence?)

  • You are very right Anant. You are today’s winner!
    Ilan Vardi has called this sequence, starting with d = 3, the Conway sequence.
    The number describes the digits in the previous entry. 3, 13 (one 3), 1113 (one 1, one 3), 3113 (three 1’s, one 3) etc.
    In mathematics, the look-and-say sequence is the sequence of integers beginning as follows:

    1, 11, 21, 1211, 111221, 312211, 13112221, 1113213211, …

    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:
    1 is read off as “one 1” or 11.
    11 is read off as “two 1s” or 21.
    21 is read off as “one 2, then one 1” or 1211.
    1211 is read off as “one 1, then one 2, then two 1s” or 111221.
    111221 is read off as “three 1s, then two 2s, then one 1” or 312211.
    The look-and-say sequence was introduced and analyzed by John Conway