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

1,10

Links

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

Example

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

Prog

(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

Crossrefs

Cf. A000720, A074813.

Sequence in context: A106142 A376994 A092512 * A073466 A062525 A085655

Adjacent sequences: A060565 A060566 A060567 * A060569 A060570 A060571

Keyword

nonn,base,easy

Author

Amarnath Murthy, Apr 27 2001

Extensions

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

Status

approved