# Maple program for A203069 from njas, Aug 16 2021
# A[i] = 0 if i not yet in sequence, otherwise 1
# ans = A203069
# sss = sequences of pairiwise sums of terms
# L = last term found
# p = parity, 0 or 1, of next term
# sm[p] = smallest missing number of parity p
# M (< 100000) = number of terms wanted

M1:=200000;
A:=Array(1..M1,0, datatype=integer[1]);
M:=1000;
A[1]:=1; ans:=[1]; sss:=[1]; L:=1; p:=1; sm[0]:=2; sm[1]:=3;
for n from 2 to M do
  p:=1-p;
  sw:=-1;
  for i from sm[p] by 2 to M1 do
    s:=L+i;
    if A[i]=0 and not isprime(s) then
        L:=i; ans:=[op(ans),L]; sss:=[op(sss),s]; A[L]:=1; sw:=1;
# update smallest missing number?
        if L=sm[p] then
                sw2:=-1;
                for j from sm[p]+2 by 2 to M1 do 
                if A[j]=0 then sm[p] := j; sw2:=1; break; fi;
                od: # od j
                if sw2=-1 then lprint("sm update failed at",n,i); break; fi;
        fi:
    break;
    fi;
  od: # od i
if sw=-1 then lprint("failed at n =",n); break; fi;
od: # od n
 ans; # A203069
 sss; # A346609