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A336752
The 'Look and Say' sequence of the concatenation of the prime numbers A033308.
0
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
1,2
COMMENTS
Concatenate all the decimal prime numbers, see A033308, then describe the resulting infinite string using the 'Look and Say' method of A005150.
LINKS
J. H. Conway and Brady Haran, Look-and-Say Numbers (2014), Numberphile video.
EXAMPLE
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.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Scott R. Shannon, Aug 15 2020
STATUS
approved