OFFSET
1,2
COMMENTS
Integers in this sequence which are themselves primes include a(2) = 3, a(7) = 29, a(8) = 37, a(19) = 197, a(34) = 619, a(40) = 853, a(42) = 937. Integers in this sequence which are themselves powers greater than 1 of primes include a(12) = 81, a(21) = 243.
FORMULA
a(n) = Sum_{i=1..n} A000015(i).
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Aug 26 2005
STATUS
approved