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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
8, 24, 28, 34, 50, 52, 58, 71, 77, 163, 197, 235, 238, 319, 570, 669, 949, 958, 1211, 1305 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..20.

Blair Kelly, Fibonacci and Lucas Factorizations.

EXAMPLE

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

CROSSREFS

Cf. A000045, A037276, A038526.

Sequence in context: A068781 A212861 A333961 * A261394 A162829 A303796

Adjacent sequences:  A038521 A038522 A038523 * A038525 A038526 A038527

KEYWORD

nonn,base,hard,more

AUTHOR

Jeff Burch

EXTENSIONS

More terms from Jens Kruse Andersen, Jan 05 2003

a(17)-a(18) from Ryan Propper, May 29 2006

a(19)-a(20) from Sean A. Irvine, Jan 16 2021

STATUS

approved

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Last modified May 13 23:41 EDT 2021. Contains 343868 sequences. (Running on oeis4.)