OFFSET
0,2
COMMENTS
See A268496 for the corresponding indices, A268494-A268495 for "late birds". We use offset 0 here because the first term has a special status (it's not really "late") and also because all related sequences (A268630 and A268494 - A268497) have a(0)=0 and omitting this term yields the corresponding "positive integer" variant.
PROG
(PARI) show(n, f="/tmp/b268497.txt", c=0, a=0, u=[a-1])={for(n=1, n, a>=u[#u]&&if(f, write(f, c++-1, " "a), print1(a", ")); u=setunion(u, [a]); while(#u>1&&u[2]==u[1]+1, u=u[^1]); for(k=u[1]+1, 9e9, !setsearch(u, k) && isprime(a*a+k) && (a=k) && break))}
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Feb 09 2016
STATUS
approved