A328223 Numbers k such that both k and k+4 are sums of two squares.

0, 1, 4, 5, 9, 13, 16, 25, 32, 36, 37, 41, 45, 49, 61, 64, 68, 81, 85, 97, 100, 109, 113, 117, 121, 144, 145, 149, 153, 160, 169, 181, 193, 196, 208, 221, 225, 229, 241, 256, 257, 261, 265, 277, 288, 289, 292, 313, 320, 324, 333, 349, 356, 361, 365, 369, 373, 388, 397, 400

Offset

1,3

Links

Table of n, a(n) for n=1..60.

Mathematica

ok[n_] := AllTrue[{0, 4}, SquaresR[2, # + n] > 0 &]; Select[Range[0, 400], ok] (* Giovanni Resta, Oct 08 2019 *)

Prog

(Magma) [k: k in [0..400] | NormEquation(1, k) eq true and NormEquation(1, k+4) eq true]; // Marius A. Burtea, Oct 08 2019

Crossrefs

Subsequence of A001481. Contains A328224 as a subsequence.

Cf. A140612, A082982, A304441.

Sequence in context: A331531 A363319 A363267 * A363282 A116045 A096818

Adjacent sequences: A328220 A328221 A328222 * A328224 A328225 A328226

Keyword

nonn

Author

Max Alekseyev, Oct 08 2019

Status

approved