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A180344 Four-digit semiprimes that are concatenation and product of two 2-digit primes. 1
1147, 1159, 1189, 1343, 1711, 1943, 1961, 2911, 2923, 3713, 4171, 4183, 4189, 4307, 4331, 4717, 5329, 5917 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

There are 18 such integers:

1147=31*37,1159=19*61,1189=29*41,1343=17*79,1711=29*59,1943=29*67,

1961=37*53,2911=41*71,2923=37*79,3713=47*79,4171=43*97,4183=47*89,

4189=59*71,4307=59*73,4331=61*71,4717=53*89,5329=73*73,5917=61*97.

Two particularly interesting cases:

1159=19*61=> 1961=37*53, 2911=41*71 =>4171=43*97.

LINKS

Table of n, a(n) for n=1..18.

EXAMPLE

1147 = concatenation of primes 11 and 47 and product of primes 31 and 37.

CROSSREFS

Sequence in context: A227478 A190924 A196779 * A031785 A274297 A074255

Adjacent sequences:  A180341 A180342 A180343 * A180345 A180346 A180347

KEYWORD

base,fini,full,nonn

AUTHOR

Zak Seidov, Jan 18 2011

STATUS

approved

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Last modified March 24 11:49 EDT 2019. Contains 321448 sequences. (Running on oeis4.)