A263930 Number of quasi-Carmichael numbers less than 10^n.

0, 2, 27, 165, 734, 3109, 11568, 40820, 137850, 457191

Offset: 1

Author

Tim Johannes Ohrtmann, Oct 30 2015

Keywords

• nonn
• more
• hard

Comments

For quasi-Carmichael numbers see A257750.

Examples

			a(1) = 0 because there are no quasi-Carmichael numbers below 10^1.
a(2) = 2 because there are two quasi-Carmichael numbers below 10^2, namely, 35 and 77.
		

Crossrefs

Cf. A055553, A216929, A257750.

Programs

Perl

use ntheory ":all"; my($s,$e)=(0,1); forcomposites { say $e++," $s" if $ >= 10**$e; $s++ if is_quasi_carmichael($) } 1e7; # Dana Jacobsen, Apr 27 2017

Extensions

a(8)-a(10) from Dana Jacobsen, Apr 27 2017