A366910 Number of n-bit binary reversible primes.

0, 1, 2, 2, 4, 6, 9, 14, 27, 36, 69, 94, 178, 308, 589, 908, 1540, 2814, 5158, 9210, 16732, 29392, 55109, 101120, 179654, 332130, 625928, 1136814, 2120399, 3963166, 7377931, 13878622, 25958590, 48421044, 92163237, 173672988, 325098134, 617741968, 1177573074, 2221353224, 4222570054

Offset

1,3

Comments

Number of primes p in [2^(n-1),2^n) whose reverse in base 2 is also prime. The count includes palindromic primes in base 2.

Links

Cathy Swaenepoel, Table of n, a(n) for n = 1..50

Cécile Dartyge, Bruno Martin, Joël Rivat, Igor E. Shparlinski, and Cathy Swaenepoel, Reversible primes, arXiv:2309.11380 [math.NT], 2023. See p. 34.

Example

The 5-bit binary reversible primes are 17="10001", 23="10111", 29="11101" and 31="11111", so a(5)=4.

Crossrefs

Cf. A074831, A074832, A117773, A048054.

Sequence in context: A025049 A293552 A293546 * A052012 A234961 A018061

Adjacent sequences: A366907 A366908 A366909 * A366911 A366912 A366913

Keyword

nonn,base

Author

Cathy Swaenepoel, Oct 27 2023

Status

approved