OFFSET
1,1
COMMENTS
This eliminates the impossibles out of A007610 and the 'or' in the title is the exclusive or.
EXAMPLE
a(3) = 5 because 5+7+11 = prime 23 and a(10) = 3 because 3+5+7+11+13+17+19+23+29+31 = 158 and half that or 79 is a prime.
MATHEMATICA
Do[k = n; a = Table[Prime[i], {i, 1, n} ]; While[ !PrimeQ[Plus @@ a] && !PrimeQ[Plus @@ a/2], k++; a = Drop[a, 1]; a = Append[a, Prime[k]]]; Print[a[[1]]], {n, 1, 100} ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Feb 16 2002
STATUS
approved