A319289 The x coordinates of the shell enumeration of N X N where N = {0, 1, 2, ...} (A319514).

0, 0, 1, 1, 2, 2, 2, 1, 0, 0, 1, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 6, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5

Offset: 0

Author

Peter Luschny, Sep 23 2018

Keywords

• nonn

Comments

See A319514 for comments and references.

Links

• Peter Luschny, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A319514.

Programs

Julia

function A319289(n)
    m = x = isqrt(n)
    y = n - x^2
    x <= y && ((x, y) = (2x - y, x))
    isodd(m) ? y : x
end