OFFSET
1,3
COMMENTS
Since A008347 has no duplicate values, a(n) must be finite. This is not true for even results of the sum.
EXAMPLE
n=5: 11-7+5=2*5-1, 13-11+7=2*5-1, 19-17+13-11+7-5+3=2*5-1, so a(5)=3.
PROG
(PARI) vb=vecsmall(500); for(k=2, 1000, forstep(l=k-1, 1, -1, t=sum(i=l, k, prime(i)*(-1)^(k-i)); if(t<500, vb[t]=vb[t]+1)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Ralf Stephan, Sep 01 2013
STATUS
approved