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A276114 Numbers k such that (101*10^k - 17)/3 is prime.

%I A276114 #17 May 25 2024 19:09:42
%S A276114 1,2,15,17,26,41,56,59,121,137,224,506,611,836,937,1079,1829,2315,
%T A276114 2666,2879,6661,7167,14021,15459,32924,73346,176815,177302
%N A276114 Numbers k such that (101*10^k - 17)/3 is prime.
%C A276114 Numbers k such that the digits 33 followed by k-1 occurrences of the digit 6 followed by the digit 1 is prime (see Example section).
%C A276114 a(29) > 2*10^5.
%H A276114 Makoto Kamada, <a href="https://stdkmd.net/nrr">Factorization of near-repdigit-related numbers</a>.
%H A276114 Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/prime_difficulty.txt">Search for 336w1</a>.
%e A276114 2 is in this sequence because (101*10^2 - 17)/3 = 3361 is prime.
%e A276114 Initial terms and associated primes:
%e A276114 a(1) = 1, 331;
%e A276114 a(2) = 2, 3361;
%e A276114 a(3) = 15, 33666666666666661;
%e A276114 a(4) = 17, 3366666666666666661;
%e A276114 a(5) = 26, 3366666666666666666666666661, etc.
%t A276114 Select[Range[0, 100000], PrimeQ[(101*10^# - 17)/3] &]
%o A276114 (PARI) is(n)=ispseudoprime((101*10^n  - 17)/3) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y A276114 Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K A276114 nonn,more
%O A276114 1,2
%A A276114 _Robert Price_, Aug 18 2016
%E A276114 a(27)-a(28) from _Robert Price_, Feb 05 2020