A221643 Numbers k such that k^2 XOR (k+1)^2 is a square, where XOR is the bitwise XOR operator.

0, 3, 4, 23, 24, 43, 44, 76, 111, 112, 115, 139, 164, 180, 183, 248, 264, 323, 327, 348, 411, 479, 480, 499, 611, 699, 747, 787, 943, 976, 1072, 1103, 1111, 1176, 1268, 1388, 1447, 1576, 1684, 1851, 1983, 1984, 2008, 2243, 2692, 3271, 3383, 3452, 3464, 3532, 3679, 3804, 3867

Offset

1,2

Links

Table of n, a(n) for n=1..53.

Prog

(Python)
import math
for i in range(4000):
    s = (i*i) ^ ((i+1)*(i+1))
    t = math.isqrt(s)
    if s == t*t:
        print(i, end=', ')

Crossrefs

Cf. A145827, A001737.

Sequence in context: A316192 A122660 A163744 * A042595 A002351 A042035

Adjacent sequences: A221640 A221641 A221642 * A221644 A221645 A221646

Keyword

nonn,base

Author

Alex Ratushnyak, Mar 27 2013

Status

approved