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 A282341 Primes p of the form x^2 + y^2 such that q = (x^2 + 1)/y^2 is a prime less than p. 1
 349, 1049, 1733, 33749, 53849, 79549, 135449, 381949, 535849, 558149, 692249, 1036349, 1156249, 1483549, 1871449, 2304349, 3097769, 6181349, 6411049, 8809049, 10355549, 11102249, 16401701, 16491521, 22867549, 26419769, 27457889, 30603049, 31728577, 34176557 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The negative Pell equation x^2 - q*y^2 = -1, hence q = (x^2 + 1)/y^2. Primes p = q are A002496. LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 EXAMPLE For prime p = 349 = 18^2 + 5^2 is q = (18^2 + 1)/5^2 = 13 prime < p. PROG (PARI) list(lim)=my(v=List(), x2, q, y, p); for(x=1, sqrtint(lim\4), x2=4*x^2; [q, y]=core(x2+1, 1); p=x2+y^2; if(q

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Last modified May 23 18:08 EDT 2022. Contains 353993 sequences. (Running on oeis4.)