OFFSET
1,1
COMMENTS
Subset of semiprimes A001358. Subset of {d = p_1 * p_2 * ... * p_m where p_i == 1 (mod 8), 1 <= i <= m are distinct primes} as occurs in Wei, p. 2.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Dasheng Wei, On the equation x^2-Dy^2=n, Feb 18, 2011.
FORMULA
MATHEMATICA
p = Select[Prime[Range[200]], Mod[#, 8] == 1 &]; Sort[Reap[Do[n=p[[i]] p[[j]]; If[n <= p[[1]]p[[-1]], Sow[n]], {i, 2, Length[p]}, {j, i - 1}]][[2, 1]]]
PROG
(PARI) list(lim)=my(v=List(), P=List(), t); forprime(p=2, lim\17, if(p%8==1, listput(P, p))); for(i=2, #P, my(p=P[i]); for(j=1, i-1, t=p*P[j]; if(t>lim, break); listput(v, t))); Set(v) \\ Charles R Greathouse IV, Jul 03 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Feb 20 2011
STATUS
approved