

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
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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}] (* JeanFrançois 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



