OFFSET

1,2

COMMENTS

All prime numbers are present and appear in their natural order; they follow a term with digital root 1.

LINKS

Carole Dubois, Table of n, a(n) for n = 1..10000

EXAMPLE

a(1) = 1 with DR (digital root) = 1 and a(2) = 2 has indeed only 1 prime factor;

a(2) = 2 with DR = 2 and a(3) = 6 has indeed 2 distinct prime factors (2 and 3);

a(3) = 6 with DR = 6 and a(4) = 30030 has indeed 6 distinct prime factors (2,3,5,7,11,13);

a(4) = 30030 with DR = 6 and a(5) = 39270 has indeed 6 distinct prime factors (2,3,5,7,11,17);

a(5) = 39270 with DR = 3 and a(6) = 30 has indeed 3 distinct prime factors (2,3,5); etc.

CROSSREFS

KEYWORD

nonn,base

AUTHOR

Eric Angelini and Carole Dubois, Aug 15 2020

STATUS

approved