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A105980
Near-repdigit primes with at least two 4's as the repeated digit.
13
443, 449, 4441, 4447, 44449, 444443, 444449, 444444443, 4444444447, 44444444441, 444444444443, 44444444444444444447, 44444444444444444444444447, 4444444444444444444444444441, 444444444444444444444444444443
OFFSET
1,1
LINKS
EXAMPLE
a(2)=449 is a term because all digits are equal to 4 except one.
MATHEMATICA
Select[Flatten[Table[FromDigits[PadLeft[{n}, x, 4]], {x, 3, 30}, {n, {1, 3, 7, 9}}]], PrimeQ] (* Harvey P. Dale, Feb 18 2018 *)
KEYWORD
base,nonn
AUTHOR
Shyam Sunder Gupta, Apr 29 2005
EXTENSIONS
More terms from Harvey P. Dale, Feb 18 2018
Name clarified by Robert Price, Sep 10 2023
STATUS
approved