OFFSET
1,1
EXAMPLE
The first odd term is a(2) = 1 and there is indeed 1 prime digit so far in the sequence (this is the 2 before 1);
The next odd term is a(8) = 3 and there are now 3 prime digits so far (2, 2 and 3);
The next odd term is a(13) = 5 and there are now 5 prime digits so far (2, 2, 3, 2 and 5); etc.
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Carole Dubois, Nov 07 2020
STATUS
approved