A336752 The 'Look and Say' sequence of the concatenation of the prime numbers A033308.

1, 2, 1, 3, 1, 5, 1, 7, 3, 1, 1, 3, 1, 1, 1, 7, 1, 1, 1, 9, 1, 2, 1, 3, 1, 2, 1, 9, 1, 3, 1, 1, 1, 3, 1, 7, 1, 4, 1, 1, 1, 4, 1, 3, 1, 4, 1, 7, 1, 5, 1, 3, 1, 5, 1, 9, 1, 6, 1, 1, 1, 6, 2, 7, 1, 1, 1, 7, 1, 3, 1, 7, 1, 9, 1, 8, 1, 3, 1, 8, 2, 9, 1, 7, 1, 1, 1, 0, 2, 1, 1, 0, 1, 3, 1, 1, 1, 0, 1, 7

Offset: 1

Author

Scott R. Shannon, Aug 15 2020

Keywords

• nonn
• base

Comments

Concatenate all the decimal prime numbers, see A033308, then describe the resulting infinite string using the 'Look and Say' method of A005150.

Examples

			The concatenation of the primes starts "23571113171923293137...".
a(1) = 1, a(2) = 2 as there is one '2' at the start of the string.
a(9) = 3, a(10) = 1 as the primes '11' and '13' from the substring '1113'. which starts with three 1's.
		

Links

• J. H. Conway and Brady Haran, Look-and-Say Numbers (2014), Numberphile video.
• Wikipedia, Look-and-say sequence.

Crossrefs

Cf. A033308, A005150, A001155, A056815, A000040.