OFFSET
0,3
COMMENTS
All terms are even, since the parity of sp(n)=A034387(n) is always the opposite of pi(n)=A000720(n). Indeed, both change by an odd amount at each prime, starting with the first nonzero values sp(2)=2 and pi(2)=1. Thus one might also consider the integer sequence a(n)/2 = 0, 0, 1, 5, 5, 15, 15, 34, 34, 34, 34, 70, 70, 123, 123, 123, 123, 203, 203, 308,.... Sequence A156778 lists these values (without duplicates).
PROG
(PARI) vector(80, n, sum(i=1, primepi(n), prime(i))*primepi(n))
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Feb 21 2009
STATUS
approved