A060568 Number of primes between n and R(n) where R(n) (A004086) is the digit reversal of n.

0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 3, 4, 6, 9, 11, 12, 15, 16, 7, 3, 0, 2, 4, 6, 9, 11, 13, 14, 8, 4, 2, 0, 2, 4, 7, 8, 10, 12, 10, 6, 4, 2, 0, 2, 4, 6, 8, 9, 12, 9, 6, 4, 2, 0, 2, 5, 7, 7, 14, 11, 9, 7, 4, 2, 0, 2, 4, 5, 15, 12, 11, 8, 6, 5, 2, 0, 2, 2, 18, 15, 13, 10, 8, 7, 4, 2, 0, 1, 20, 16, 14

Offset: 1

Author

Amarnath Murthy, Apr 27 2001

Keywords

• nonn
• base
• easy

Examples

			a(10) = 4, as there are four primes between 10 and 1.
		

Links

• John Tyler Rascoe, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000720, A074813.

Programs

Python

from sympy import primerange
def A060568(n):
    x = (n, int(str(n)[::-1],10))
    return len([i for i in primerange(min(x)+1,max(x))]) # John Tyler Rascoe, Jan 13 2025

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), May 10 2001