A048744 -id:A048744 - cp's OEIS frontend

A088110 Numbers n such that 2^n + n and 2^n - n are noncomposite.

0, 1, 3, 9

Offset: 1

Amarnath Murthy, Sep 25 2003

Conjecture: sequence is finite.

No more terms < 88075. - David Wasserman, Jul 20 2005

			9 is a member as 2^9 + 9 = 521 and 2^9 - 9 = 503 are primes.

Cf. A048744, A052007.

[0,1] cat [n: n in [0..1000] | IsPrime(2^n+n) and IsPrime(2^n-n)]; // Vincenzo Librandi, Dec 08 2015

Join[{0, 1}, Select[Range[1000], PrimeQ[2^# + #] && PrimeQ[2^# -#] &]] (* Vincenzo Librandi, Dec 08 2015 *)

A224506 Numbers k such that 9^k - k is prime.

Original entry on oeis.org

2, 70, 88, 6562, 9100, 11758, 34334, 39212, 120590

Offset: 1

Alex Ratushnyak, Apr 08 2013

a(7) > 20000. - Giovanni Resta, Apr 09 2013

a(10) > 2*10^5. - Robert Price, Mar 12 2014

Cf. A048744, A058037, A057908, A058046, A058829, A224470, A224471.

Select[Range[1000], PrimeQ[9^# - #] &] (* Alonso del Arte, Apr 11 2013 *)

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

a(6) from Giovanni Resta, Apr 09 2013

a(7)-a(9) from Robert Price, Mar 12 2014

A295111 Primes p such that 2^p - p is also a prime.

Original entry on oeis.org

2, 3, 13, 19, 481801

Offset: 1

Iain Fox, Nov 14 2017

a(6) > 1061095.
Intersection of A000040 and A048744.
Since numbers other than 3 that are congruent to 3 mod 6 are composite, for n > 2, a(n) is congruent to 1 mod 6 (see comments by Iain Fox in A048744).

			p=13, 2^13 - 13 = 8179 is prime.

Cf. A000325, A081296, A048744, A057663, A057673.

lista(nn) = forprime(p=2, nn, if(ispseudoprime(2^p - p), print1(p, ", ")))

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A088110 Numbers n such that 2^n + n and 2^n - n are noncomposite.

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A224506 Numbers k such that 9^k - k is prime.

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A295111 Primes p such that 2^p - p is also a prime.

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