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

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

Offset

1,2

Comments

For quasi-Carmichael numbers see A257750.

Links

Table of n, a(n) for n=1..10.

Example

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.

Prog

(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

Crossrefs

Cf. A055553, A216929, A257750.

Sequence in context: A166942 A119351 A098627 * A051766 A058406 A216087

Adjacent sequences: A263927 A263928 A263929 * A263931 A263932 A263933

Keyword

nonn,more,hard

Author

Tim Johannes Ohrtmann, Oct 30 2015

Extensions

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

Status

approved