OFFSET
1,1
EXAMPLE
a(3) = 31 since a(1)+a(2) is 16 and 31, whose index equals 11, is the first odd-indexed prime which meets the criteria. 16 + 7 = 23, a prime, but 7 is the 4th prime and therefore cannot be used.
MATHEMATICA
f[s_List] := Block[{p = s[[-2]] + s[[-1]], q = 17}, While[ !PrimeQ[p + q] || MemberQ[s, q], q = NextPrime[q, 2]]; Append[s, q]]; Nest[f, {5, 11}, 56]
PROG
(PARI) v=[5, 11]; n=1; while(n<100, p=prime(2*n-1); if(isprime(v[#v]+v[#v-1]+p)&&!vecsearch(vecsort(v), p), v=concat(v, p); n=0); n++); v \\ Derek Orr, May 13 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, May 05 2015
STATUS
approved