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A105975 Near-repdigit primes with 9 as repeated digit. 9

%I #11 Jun 16 2018 22:16:08

%S 199,499,599,919,929,991,997,1999,2999,4999,8999,9199,9929,9949,49999,

%T 59999,79999,94999,98999,99929,99989,99991,199999,599999,799999,

%U 989999,991999,999199,999499,999599,999959,999979,2999999,4999999,9899999

%N Near-repdigit primes with 9 as repeated digit.

%H Harvey P. Dale, <a href="/A105975/b105975.txt">Table of n, a(n) for n = 1..1000</a>

%H Brady Haran and Simon Pampena, <a href="https://www.youtube.com/watch?v=HPfAnX5blO0">Glitch Primes and Cyclops Numbers</a>, Numberphile video (2015)

%e a(2)=499 is a term because all digits are equal to 9 except one.

%t Sort[Select[Flatten[Table[FromDigits/@(Flatten[Permutations/@Table[ Join[{n},PadRight[{},i,9]],{n,{1,2,4,5,7,8}}],1]),{i,2,6}]],PrimeQ]] (* _Harvey P. Dale_, May 07 2015 *)

%K base,nonn

%O 1,1

%A _Shyam Sunder Gupta_, Apr 29 2005

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Last modified April 24 20:08 EDT 2024. Contains 371963 sequences. (Running on oeis4.)