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A105992 Near-repunit primes. 7
101, 113, 131, 151, 181, 191, 211, 311, 811, 911, 1117, 1151, 1171, 1181, 1511, 1811, 2111, 4111, 8111, 10111, 11113, 11117, 11119, 11131, 11161, 11171, 11311, 11411, 16111, 101111, 111119, 111121, 111191, 111211, 111611, 112111, 113111, 131111, 311111, 511111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

C. Caldwell and H. Dubner, "The near repunit primes 1(n-k-1)01(1k)," J. Recreational Math., 27 (1995) 35-41.

Heleen, J. P., "More near-repunit primes 1(n-k-1)D(1)1(k), D=2,3, ..., 9," J. Recreational Math., 29:3 (1998) 190-195.

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

Chris Caldwell, The Top 20 Near-repdigit Primes

Chris Caldwell, The Prime Glossary, Near-repunit prime

EXAMPLE

a(2)=113 is a term because 113 is a prime and all digits are 1 except one.

MATHEMATICA

lst = {}; Do[r = (10^n - 1)/9; Do[AppendTo[lst, DeleteCases[Select[FromDigits[Permutations[Append[IntegerDigits[r], d]]], PrimeQ], r]], {d, 0, 9}], {n, 2, 14}]; Sort[Flatten[lst]] (* Arkadiusz Wesolowski, Sep 20 2011 *)

CROSSREFS

Cf. A000042, A002275, A004022, A046053, A046413, A065074, A034093, A065083, A102782, A118505.

Sequence in context: A069691 A084414 A164937 * A038370 A084430 A182693

Adjacent sequences:  A105989 A105990 A105991 * A105993 A105994 A105995

KEYWORD

base,nonn

AUTHOR

Shyam Sunder Gupta, Apr 29 2005

STATUS

approved

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Last modified December 15 09:05 EST 2019. Contains 329995 sequences. (Running on oeis4.)