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%I #11 Oct 03 2022 13:16:08
%S 3,31,37,311,311111,31111111111,311111111111,377777777777,
%T 31111111111111,377777777777777777,
%U 31111111111111111111111111111111111,311111111111111111111111111111111111111111111111
%N Primes of the form identical digits preceded by a 3.
%H Vincenzo Librandi, <a href="/A090151/b090151.txt">Table of n, a(n) for n = 1..18</a>
%t Select[ FromDigits /@ Flatten[ Table[ PadRight[{3}, i, # ] & /@ {1, 2, 3, 4, 5, 6, 7, 8, 9}, {i, 2, 24}], 1], PrimeQ[ # ] &]
%t Select[Union[Flatten[Table[FromDigits[PadRight[{3},n,c]],{n,1000},{c,{1,7}}]]],PrimeQ] (* _Harvey P. Dale_, Oct 03 2022 *)
%o (Python)
%o from sympy import isprime
%o def afind(terms):
%o print(3, end=", ")
%o digits, n = 1, 1
%o while n < terms:
%o for id in "17":
%o t = int('3' + id*digits)
%o if isprime(t): print(t, end=", "); n += 1
%o digits += 1
%o afind(12) # _Michael S. Branicky_, Mar 31 2021
%K nonn,base
%O 1,1
%A _Robert G. Wilson v_, Nov 22 2003
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