A105352 Numbers of points on successive rings of the simple square lattice.

1, 4, 4, 4, 8, 4, 4, 8, 8, 4, 8, 4, 8, 12, 8, 8, 4, 8, 4, 8, 8, 8, 8, 4, 12, 8, 8, 8, 8, 4, 16, 8, 4, 8, 8, 8, 4, 8, 16, 8, 8, 8, 4, 12, 8, 8, 8, 8, 8, 8, 8, 4, 8, 16, 4, 16, 8, 8, 4, 16, 8, 8, 8, 8, 8, 8, 4, 8, 12, 16, 8, 8, 8, 8, 16, 8, 8, 4, 8, 12, 8, 16, 8, 8, 8, 16, 12, 8, 8, 8, 8, 8, 8, 4, 8, 8, 16, 4

Offset

1,2

Comments

This is A004018 with the zero terms omitted.

a(n) = A004018(A001481(n)). - Franz Vrabec, Jun 14 2005

Links

T. D. Noe, Table of n, a(n) for n = 1..10000

Example

a(1) = 1 from (0, 0).
a(2) = 4 from (0, 1), (0, -1), (1, 0), (-1, 0).
a(5) = 8 from (+-1, +-2), (+-2, +-1).

Mathematica

max = 100; A001481 = Select[Range[0, 4*max], SquaresR[2, #] != 0 &]; A004018[n_] := SquaresR[2, n]; a[n_] := A004018[A001481[[n]]]; Table[a[n], {n, 1, max}] (* Jean-François Alcover, Oct 04 2013, after Franz Vrabec *)

Crossrefs

Cf. A004018, A001481; A057961 (partial sums).

Sequence in context: A010658 A128939 A342484 * A132200 A110757 A377468

Adjacent sequences: A105349 A105350 A105351 * A105353 A105354 A105355

Keyword

nice,nonn

Author

Sébastien Dumortier, Apr 30 2005

Extensions

Definition revised by N. J. A. Sloane, Oct 04 2013

Status

approved