[seqfan] Two neighboring digits multiply to a composite
Eric Angelini
Eric.Angelini at kntv.be
Wed Apr 18 02:15:50 CEST 2012
More on the same idea:
Smallest integer not yet in C such that
two neighboring digits multiply to a
composite:
C = 1,4,2,3,4,5,6,7,8,9,14,16,18,19,22,
23,24,25,26,27,28,29,32,33,34,35,36,
37,38,39,41,42,43,44,45,46,47,48,49,
52,53,54,55,56,57,58,59,61,62,63,64,
65,66,67,68,69,72,73,74,75,76,77,78,
79,81,82,83,84,85,86,87,88,89,91,92,
93,94,95,96,97,98,99,141,414,161,...
Best,
É.
(and what about Z: smallest integer
not yet present in Z such that two
neighboring digits don't multiply to
a prime nor a composite. ;-)
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