This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A141165 #38 Feb 29 2020 18:10:26 %S A141165 3,5,11,17,19,43,61,71,83,97,103,149,151,167,181,233,271,277,293,307, %T A141165 311,337,367,373,397,401,409,421,431,433,457,463,467,491,557,569,587, %U A141165 631,641,661,673,683,701,733,743,751,757,769,787,821,859,863,883,911 %N A141165 Primes of the form 9*x^2+7*x*y-5*y^2. %C A141165 Discriminant = 229. Class = 3. Binary quadratic forms a*x^2+b*x*y+c*y^2 have discriminant d=b^2-4ac. They can represent primes only if gcd(a,b,c)=1. [Edited by _M. F. Hasler_, Jan 27 2016] %C A141165 Also primes represented by the improperly equivalent form 5*x^2+7*x*y-9*y^2. - _Juan Arias-de-Reyna_, Mar 17 2011 %C A141165 36*a(n) has the form z^2 - 229*y^2, where z = 18*x+7*y. [_Bruno Berselli_, Jun 25 2014] %C A141165 Appears to be the complement of A141166 in A268155, primes that are squares mod 229. - _M. F. Hasler_, Jan 27 2016 %D A141165 Z. I. Borevich and I. R. Shafarevich, Number Theory %D A141165 D. B. Zagier, Zetafunktionen und quadratische Körper %H A141165 Juan Arias-de-Reyna, <a href="/A141165/b141165.txt">Table of n, a(n) for n = 1..10000</a> %H A141165 Peter Luschny, <a href="https://oeis.org/wiki/User:Peter_Luschny/BinaryQuadraticForms#Implementation">Binary Quadratic Forms</a> %H A141165 N. J. A. Sloane et al., <a href="https://oeis.org/wiki/Binary_Quadratic_Forms_and_OEIS">Binary Quadratic Forms and OEIS</a> (Index to related sequences, programs, references) %e A141165 a(10)=97 because we can write 97= 9*3^2+7*3*1-5*1^2 %t A141165 q := 9*x^2 + 7*x*y - 5*y^2; pmax = 1000; xmax = xmax0 = 50; ymin = ymin0 = -50; ymax = ymax0 = 50; k = 1.3 (expansion coeff. for maxima *); prms0 = {}; prms = {2}; While[prms != prms0, xx = yy = {}; prms0 = prms; prms = Reap[Do[p = q; If[2 <= p <= pmax && PrimeQ[p], AppendTo[xx, x]; AppendTo[yy, y]; Sow[p]], {x, 1, If[xmax == xmax0, xmax, Floor[k*xmax]]}, {y, If[ymin == ymin0, ymin, Floor[k*ymin]], If[ymax == ymax0, ymax, Floor[k*ymax]]}]][[2, 1]] // Union; xmax = Max[xx]; ymin = Min[yy]; ymax = Max[yy]; Print[Length[prms], " terms", " xmax = ", xmax, " ymin = ", ymin, " ymax = ", ymax ]]; A141165 = prms (* _Jean-François Alcover_, Oct 26 2016 *) %o A141165 (PARI) is_A141165(p)=qfbsolve(Qfb(9,7,-5),p) \\ Returns nonzero (actually, a solution [x,y]) iff p is a member of the sequence. For efficiency it is assumed that p is prime. - _M. F. Hasler_, Jan 27 2016 %o A141165 (Sage) # uses[binaryQF] %o A141165 # The function binaryQF is defined in the link 'Binary Quadratic Forms'. %o A141165 Q = binaryQF([9, 7, -5]) %o A141165 print(Q.represented_positives(911, 'prime')) # _Peter Luschny_, Oct 26 2016 %Y A141165 Cf. A038872 (d=5). A038873 (d=8). A068228, A141123 (d=12). A038883 (d=13). A038889 (d=17). A141111, A141112 (d=65). A141166 (d=229). %Y A141165 For a list of sequences giving numbers and/or primes represented by binary quadratic forms, see the "Binary Quadratic Forms and OEIS" link. %K A141165 nonn %O A141165 1,1 %A A141165 Laura Caballero Fernandez, Lourdes Calvo Moguer, Maria Josefa Cano Marquez, Oscar Jesus Falcon Ganfornina and Sergio Garrido Morales (sergarmor(AT)yahoo.es), Jun 12 2008