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A105993 Near-repunit semiprimes. 1

%I

%S 115,118,119,121,141,161,411,511,611,1011,1101,1114,1115,1119,1121,

%T 1141,1191,1211,1411,1711,5111,7111,9111,11101,11114,11141,11181,

%U 11611,11911,13111,14111,17111,18111,19111,31111,61111,91111,110111,111011,111101

%N Near-repunit semiprimes.

%H Harvey P. Dale, <a href="/A105993/b105993.txt">Table of n, a(n) for n = 1..1000</a>

%e a(2)=118 is a term because 118 is a semiprime and all digits are 1 except one.

%t Select[Sort[Flatten[Table[FromDigits/@Permutations[PadRight[{k},n,1]],{n,3,6},{k,Range[0,9]}]]],PrimeOmega[#]==2&&Length[Union[ IntegerDigits[ #]]]>1&] (* _Harvey P. Dale_, Jun 13 2020 *)

%K base,nonn

%O 1,1

%A _Shyam Sunder Gupta_, Apr 29 2005

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Last modified March 4 02:36 EST 2021. Contains 341773 sequences. (Running on oeis4.)