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A243651 Nonnegative integers of the form x^2+11y^2. 1
0, 1, 4, 9, 11, 12, 15, 16, 20, 25, 27, 36, 44, 45, 47, 48, 49, 53, 60, 64, 69, 75, 80, 81, 92, 93, 99, 100, 103, 108, 111, 115, 121, 124, 125, 132, 135, 144, 148, 155, 163, 165, 169, 176, 177, 180, 185, 188, 192, 196, 199, 201, 207, 212, 213, 220, 225, 236, 240, 243, 256, 257, 267, 268, 269, 275 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Discriminant -44.

LINKS

Table of n, a(n) for n=0..65.

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, 11, 500);

CROSSREFS

Primes: A033209.

Sequence in context: A000974 A291626 A312833 * A292673 A035233 A341788

Adjacent sequences:  A243648 A243649 A243650 * A243652 A243653 A243654

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jun 08 2014

STATUS

approved

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Last modified June 12 14:15 EDT 2021. Contains 344956 sequences. (Running on oeis4.)