A318568 Primes p such that 2^p reversed is a prime.

5, 7, 17, 37, 107, 137, 271

Offset: 1

Author

Vincenzo Librandi, Sep 22 2018

Keywords

• nonn
• base
• more

Comments

Equivalently, primes in A057708. - Muniru A Asiru, Dec 25 2018

a(8) > 200000 using A057708. - Michael S. Branicky, May 17 2025

Crossrefs

Cf. A059706.

Subsequence of A057708.

Programs

GAP

P0:=List(List([1..300],j->Reversed(ListOfDigits(2^j))),k->Sum([1..Size(k)],i->k[i]*10^(Size(k)-i)));;
a:=Filtered([1..Length(P0)],m->IsPrime(m) and IsPrime(P0[m]));; Print(a); # Muniru A Asiru, Dec 25 2018

Magma

[p: p in PrimesUpTo(200) | IsPrime(Seqint(Reverse(Intseq(2^p))))];

Mathematica

Select[Prime[Range[100]], PrimeQ[ToExpression[StringReverse[ToString[2^#]]]] &]

PARI

isok(p) = isprime(p) && isprime(fromdigits(Vecrev(digits(2^p)))); \\ Michel Marcus, Sep 22 2018