A105993 Near-repunit semiprimes.

115, 118, 119, 121, 141, 161, 411, 511, 611, 1011, 1101, 1114, 1115, 1119, 1121, 1141, 1191, 1211, 1411, 1711, 5111, 7111, 9111, 11101, 11114, 11141, 11181, 11611, 11911, 13111, 14111, 17111, 18111, 19111, 31111, 61111, 91111, 110111, 111011, 111101

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

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

Mathematica

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 *)

Crossrefs

Sequence in context: A101111 A129823 A056035 * A036269 A036462 A020443

Adjacent sequences: A105990 A105991 A105992 * A105994 A105995 A105996

Keyword

base,nonn

Author

Shyam Sunder Gupta, Apr 29 2005

Status

approved