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A038524 Numbers n such that the n-th Fibonacci number is composite and the concatenation of its prime factors (written in base 10 in ascending order) is prime. 0

%I

%S 8,24,28,34,50,52,58,71,77,163,197,235,238,319,570,669,949,958,1211,

%T 1305

%N Numbers n such that the n-th Fibonacci number is composite and the concatenation of its prime factors (written in base 10 in ascending order) is prime.

%H Blair Kelly, <a href="http://mersennus.net/fibonacci/">Fibonacci and Lucas Factorizations</a>.

%e F(24) = 46368 = 2^5 * 3^2 * 7 * 23 is composite and the concatenation 2222233723 is prime, so 24 is in the sequence.

%Y Cf. A000045, A037276, A038526.

%K nonn,base,hard,more

%O 1,1

%A _Jeff Burch_

%E More terms from _Jens Kruse Andersen_, Jan 05 2003

%E a(17)-a(18) from _Ryan Propper_, May 29 2006

%E a(19)-a(20) from _Sean A. Irvine_, Jan 16 2021

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Last modified June 23 23:39 EDT 2021. Contains 345403 sequences. (Running on oeis4.)