

A226178


Exponents n such that 2^n  previous_prime(2^n) = next_prime(2^n)  2^n.


0




OFFSET

1,1


COMMENTS

The differences next_prime(2^n)  2^n are respectively: 1, 3, 3, 15, 165, 1035, 663.


LINKS

Table of n, a(n) for n=1..7.


EXAMPLE

2^6 = 64, next prime = 67, previous prime = 61, 6764 = 6461 = 3, hence 6 is in the sequence.


MATHEMATICA

Reap[Do[m = 2^n; p = NextPrime[m, 1]; q = NextPrime[m]; If[p + q == 2*m, Print[n]; Sow[n]], {n, 2, 10^4}]][[2, 1]]


PROG

(PARI) isok(n) = my(p=2^n); pprecprime(p1) == nextprime(p+1)  p; \\ Michel Marcus, Oct 02 2019


CROSSREFS

Cf. A000079, A014210, A014234, A117387, A145025.
Sequence in context: A107763 A166470 A144144 * A129085 A274941 A141288
Adjacent sequences: A226175 A226176 A226177 * A226179 A226180 A226181


KEYWORD

nonn,more


AUTHOR

JeanFrançois Alcover, May 30 2013


EXTENSIONS

Offset 1 from Michel Marcus, Oct 02 2019


STATUS

approved



