This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A139668 Primes of the form x^2 + 1848*y^2. 6
 1873, 2017, 2137, 2377, 2473, 2689, 3217, 3529, 3697, 4057, 4657, 5569, 6073, 6337, 7177, 7393, 7417, 7561, 7681, 7753, 8017, 8089, 8233, 8353, 8737, 8761, 9241, 9601, 9769, 11113, 11257, 11617, 12049, 12433, 12457, 12721, 13297, 13633, 13729, 14281, 15073, 15313, 16417, 16633, 16657, 16921, 16993, 17257, 17977, 18313, 18481, 19009, 19273, 19441, 20113 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Discriminant = -7392. The primes are congruent to {1, 25, 169, 289, 361, 529, 625, 697, 793, 841, 961, 1345, 1369, 1633, 1681} (mod 1848). More than the usual number of terms are shown in order to display the difference from A244019. - N. J. A. Sloane, Jun 19 2014 LINKS Vincenzo Librandi and Ray Chandler, Table of n, a(n) for n = 1..10000 (first 1000 terms from Vincenzo Librandi). William C. Jagy and Irving Kaplansky, Positive definite binary quadratic forms that represent the same primes [Cached copy] N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references) MAPLE fd:=proc(a, b, c, M) local dd, xlim, ylim, x, y, t1, t2, t3, t4, i; dd:=4*a*c-b^2; if dd<=0 then error "Form should be positive definite."; break; fi; t1:={}; xlim:=ceil( sqrt(M/a)*(1+abs(b)/sqrt(dd))); ylim:=ceil( 2*sqrt(a*M/dd)); for x from 0 to xlim do for y from -ylim to ylim do t2 := a*x^2+b*x*y+c*y^2; if t2 <= M then t1:={op(t1), t2}; fi; od: od: t3:=sort(convert(t1, list)); t4:=[]; for i from 1 to nops(t3) do    if isprime(t3[i]) then t4:=[op(t4), t3[i]]; fi; od: [[seq(t3[i], i=1..nops(t3))], [seq(t4[i], i=1..nops(t4))]]; end; fd(1, 0, 1848, 50000); # N. J. A. Sloane, Jun 19 2014 MATHEMATICA QuadPrimes2[1, 0, 1848, 10000] (* see A106856 *) PROG (MAGMA) [ p: p in PrimesUpTo(15000) | p mod 1848 in {1, 25, 169, 289, 361, 529, 625, 697, 793, 841, 961, 1345, 1369, 1633, 1681}]; // Vincenzo Librandi, Jul 29 2012 (MAGMA) k:=1848; [p: p in PrimesUpTo(21000) | NormEquation(k, p) eq true]; // Bruno Berselli, Jun 01 2016 CROSSREFS Cf. A244019 (a different sequence which agrees for the first 43 terms), A106856. Sequence in context: A270244 A154675 A068281 * A244019 A054818 A127410 Adjacent sequences:  A139665 A139666 A139667 * A139669 A139670 A139671 KEYWORD nonn,easy AUTHOR T. D. Noe, Apr 29 2008 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 20 23:29 EDT 2019. Contains 325189 sequences. (Running on oeis4.)