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A254718
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a(n) is the least semiprime having a(n-1) as a substring, a(1)=4.
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1
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4, 14, 141, 1141, 11141, 111413, 1111413, 11114137, 111114137, 1111141373, 11111141373, 111111413737, 1111114137373, 11111141373734, 1111114137373402, 11111141373734023, 111111413737340234, 11111114137373402349, 111111114137373402349, 1111111141373734023499
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OFFSET
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1,1
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LINKS
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EXAMPLE
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4=2*2, 14=2*7, 141=3*47, 1141=7*163, 11141=13*857, 111413=43*2591, 1111413=3*370471, 11114137=47*236471, 111114137=31*3584327, 1111141373=1051*1057223.
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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