A271109 -id:A271109 - cp's OEIS frontend

A271340 Numbers k such that (14*10^k + 73)/3 is prime.

0, 1, 2, 3, 4, 6, 7, 10, 15, 19, 32, 54, 68, 114, 148, 227, 238, 286, 405, 789, 857, 1310, 2314, 3613, 4103, 4215, 5135, 6094, 8023, 8718, 16899, 34215, 41989, 81585, 85010, 143097, 165282, 199447

Offset: 1

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Robert Price, Apr 05 2016

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For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 6 followed by the digits 91 is prime (see Example section).

a(39) > 2*10^5.

			3 is in this sequence because (14*10^3 + 73)/3 = 4691 is prime.
Initial terms and associated primes:
a(1) = 0, 29;
a(2) = 1, 71;
a(3) = 2, 491;
a(4) = 3, 4691;
a(5) = 4, 46691;
a(6) = 6, 4666691, etc.

Makoto Kamada, Search for 46w91.

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271109, A271269.

Select[Range[0, 100000], PrimeQ[(14*10^# + 73)/3] &]

is(n)=ispseudoprime((14*10^n + 73)/3) \\ Charles R Greathouse IV, Jun 13 2017

a(36)-a(38) from Robert Price, Dec 26 2018

cp's OEIS Frontend

A271340 Numbers k such that (14*10^k + 73)/3 is prime.

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