A090649 -id:A090649 - cp's OEIS frontend

A217385 Numbers n such that 9^n + 8 is prime.

1, 2, 4, 7, 10, 19, 22, 44, 62, 76, 122, 2191, 3134, 9244, 40999, 48230

Offset: 1

Vincenzo Librandi, Oct 04 2012

Contains exactly the halved even terms of A217136. - Bruno Berselli, Oct 04 2012

Mathematica
```
Select[Range[5000], PrimeQ[9^# + 8] &]
```

is(n)=ispseudoprime(9^n+8) \\ Charles R Greathouse IV, Jun 13 2017

a(14) from Bruno Berselli, Oct 05 2012

a(15)-a(16) derived from A217136 by Robert Price, May 19 2015

A248547 Numbers n such that 75^n+2 is prime.

Original entry on oeis.org

0, 12, 28, 53, 65, 504, 1967, 6915

Offset: 1

Vaclav Kotesovec, Oct 08 2014

Dedicated to N. J. A. Sloane for his 75th birthday!
Next term, if it exists, is greater than 10000.
Next term, if it exists, is greater than 50000. - Michael S. Branicky, May 21 2025

Cf. A051783, A087885, A090649, A109076, A138048, A113480, A138049, A138050.

[n: n in [0..200] | IsPrime(75^n+2)]; // Vincenzo Librandi, Oct 08 2014

Select[Range[0, 1000], PrimeQ[75^# + 2] &]

is(n)=ispseudoprime(75^n+2) \\ Charles R Greathouse IV, Jun 13 2017

cp's OEIS Frontend

A217385 Numbers n such that 9^n + 8 is prime.

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