OFFSET
1,3
COMMENTS
a(n)/A074949(n) is the asymptotic density of numbers that are divisible by their digital root in base n+1 (e.g., A064807 for base 10). - Amiram Eldar, Nov 24 2022
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..2308
EXAMPLE
1, 1, 5/6, 5/6, 37/60, 47/60, 69/140, 263/420, 1321/2520, 1429/2520, ...
MATHEMATICA
a[n_] := Numerator @ Sum[1/LCM[k, n], {k, 1, n}]; Array[a, 30] (* Amiram Eldar, Jan 31 2021 *)
PROG
(PARI) a(n)=numerator(sum(i=1, n, 1/lcm(n, i)))
CROSSREFS
KEYWORD
easy,frac,nonn
AUTHOR
Benoit Cloitre, Oct 05 2002
STATUS
approved