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 A242664 #19 Jun 26 2025 10:47:41
%S A242664 0,1,4,6,9,10,15,16,24,25,26,31,36,39,40,41,49,54,60,64,65,71,74,79,
%T A242664 81,86,89,90,96,100,104,106,111,121,124,129,134,135,144,150,151,156,
%U A242664 159,160,164,166,169,185,186,191,196,199,201,214,215,216,225,234,239,240,241,246,249,250,256,260,265,271,279,281,284,289,294,296
%N A242664 Nonnegative integers of the form x^2 + 6xy - y^2.
%C A242664 Discriminant 40.
%C A242664 Nonnegative integers of the form x^2 - 10y^2. - _Jon E. Schoenfield_, Jun 03 2022
%H A242664 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)
%t A242664 Reap[For[n = 0, n <= 300, n++, If[Reduce[ x^2 + 6*x*y - 1*y^2 == n, {x, y}, Integers] =!= False, Sow[n]]]][[2, 1]]
%t A242664 Select[Range[0, 300], Reduce[x^2 + 6 x y - y^2 == #, {x, y}, Integers] =!= False &] (* _Ed Pegg Jr_, Jun 26 2025 *)
%Y A242664 Primes in this sequence = A141180.
%K A242664 nonn
%O A242664 1,3
%A A242664 _N. J. A. Sloane_, May 31 2014