OFFSET
1,2
COMMENTS
The corresponding lucky numbers, A000959(a(n)) are 1, 21, 195, 205, 1575, 68827, 435019, 435123, 2732355, 2732505, 17151283, 682241721, ...
The corresponding quotients A000959(a(n))/a(n) are 1, 3, 5, 5, 7, 11, 13, 13, 15, 15, 17, 21, ...
a(13) > 4*10^9, if it exists. - Giovanni Resta, May 10 2020
EXAMPLE
7 is in the sequence since the 7th lucky number, 21 = 3 * 7 is divisible by 7.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Nov 15 2019
STATUS
approved