OFFSET
0,1
EXAMPLE
For n=0, 10 = 7 + 3 is the smallest even number such that there is no prime between 7 and 10, so a(0)=10;
for n=1, 4 = 2 + 2 is the smallest even number such that there is only one prime between 2 and 4, which is 3, so a(1)=4;
for n=2, 128 = 109 + 19, there are two primes between 109 and 128, which are 113 and 127, for which a(n)-p = 15 and 1 respectively, and both nonprime. There is no smaller even number having exactly 2 such primes, so a(2)=128.
MATHEMATICA
fa = {}; n = 2; efa = 0; While[efa < 37, n = n + 2; p = NextPrime[n];
ct = 0; While[p = NextPrime[p, -1]; ! PrimeQ[n - p], ct++];
While[ct > (Length[fa] - 2), AppendTo[fa, 0]];
If[fa[[ct + 1]] == 0, fa[[ct + 1]] = n];
While[fa[[efa + 1]] > 0, efa++]]; Part[fa, 1;; efa]
CROSSREFS
KEYWORD
nonn
AUTHOR
Lei Zhou, Aug 01 2018
STATUS
approved