login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A239397 Prime Gaussian integers x + y*i sorted by norm and increasing y, with x and y nonnegative. 5
1, 1, 2, 1, 1, 2, 3, 0, 0, 3, 3, 2, 2, 3, 4, 1, 1, 4, 5, 2, 2, 5, 6, 1, 1, 6, 5, 4, 4, 5, 7, 0, 0, 7, 7, 2, 2, 7, 6, 5, 5, 6, 8, 3, 3, 8, 8, 5, 5, 8, 9, 4, 4, 9, 10, 1, 1, 10, 10, 3, 3, 10, 8, 7, 7, 8, 11, 0, 0, 11, 11, 4, 4, 11, 10, 7, 7, 10, 11, 6, 6, 11, 13, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

After the number 1 + i, there are exactly two Gaussian primes here for each norm in A055025; if x + y*i is here, then y + x*i is also. - T. D. Noe, Mar 26 2014

Sequence A239621 provides a more condensed version, without y + x*i following each x + y*i. The real parts and imaginary parts are listed in A300587 and A300588. - M. F. Hasler, Mar 09 2018

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10002 (5001 complex numbers)

Eric Weisstein's World of Mathematics, Gaussian prime

Wikipedia, Complex Number

FORMULA

a(4n + 1) = a(4n) = A239621(2n) = A300588(n), a(4n + 2) = a(4n-1) = A239621(2n-1) = A300587(n). - M. F. Hasler, Mar 09 2018

EXAMPLE

The sequence of Gaussian primes (with nonnegative real and imaginary part) begins 1+i, 2+i, 1+2i, 3, 3i,...

MATHEMATICA

mx = 20; lst = Flatten[Table[{a, b}, {a, 0, mx}, {b, 0, mx}], 1]; qq = Select[lst, Norm[#] <= mx && PrimeQ[#[[1]] + I*#[[2]], GaussianIntegers -> True] &]; Sort[qq, Norm[#1] < Norm[#2] &]

PROG

(PARI) is_GP(x, y=0)={(x=factor(if(imag(x+I*y), x+I*y, I*x+y)))&&vecsum(x[, 2])==1+(abs(x[1, 1])==1)} \\ Returns 1 iff x + iy (y may be omitted) is a Gaussian prime. -  M. F. Hasler, Mar 10 2018

(PARI) for(N=2, 499, if(isprime(N) && N%4<3, z=factor(I*N); for(i=0, N>2, print1(real(z[i+1, 1])", "imag(z[i+1, 1])", ")), issquare(N, &z) && isprime(z) && z%4==3 && print1(z", 0, 0, "z", ")) \\ M. F. Hasler, Mar 10 2018

CROSSREFS

Cf. A055025 (norms of Gaussian primes), A239621, A300587, A300588.

Sequence in context: A191620 A214751 A306512 * A307884 A177858 A166967

Adjacent sequences:  A239394 A239395 A239396 * A239398 A239399 A239400

KEYWORD

nonn,easy

AUTHOR

T. D. Noe, Mar 22 2014

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 22 14:32 EDT 2019. Contains 323480 sequences. (Running on oeis4.)