[seqfan] Primes with strokes (wrong start)

[Éric Angelini]

David S. just wrote to me about S.
Here is my answer.
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Hello David,
thanks for your comments,
well this seq is easy to start by hand
as we lexicographically care about S,
not the primes!

> concatenated digits between two strokes is prime."
S = 1,3,2,4,7,5,6,8,9,10,11,14,16,18,83,13,17

a(1)=1 is ok
a(2) cannot be 2 as 2 is a prime digit
and if we strike it is not ok: 12 is a
composite. We then try a(2)=3 and
it works as 13 is prime.
a(3)=2 is ok too as 2 is a prime between 
two strokes
a(4)=4 is the smallest available integer
not leading to an immediate contradiction 
a(5) cannot be 5 as a stroke after 5
would produce the composite 45. But
a(5)=6 is ok -- as 6 is the smallest 
available integer not leading to an 
immediate contradiction; so my seq 
is wrong. Back to the blackboard!
Thanks for your sharp eye, David!
(going now for a lunch -- will fix this
later this afternoon)...
Best,
É.