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A105352 Numbers of points on successive rings of the simple square lattice. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A211639 A010658 A128939 * A132200 A110757 A167184

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

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Last modified February 24 07:19 EST 2020. Contains 332199 sequences. (Running on oeis4.)