

A103300


Number of perfect rulers with length n (n>=0).


27



1, 1, 1, 2, 3, 4, 2, 12, 8, 4, 38, 30, 14, 6, 130, 80, 32, 12, 500, 326, 150, 66, 18, 4, 944, 460, 166, 56, 12, 6, 2036, 890, 304, 120, 20, 10, 2, 2678, 974, 362, 100, 36, 4, 2, 4892, 2114, 684, 238, 68, 22, 4, 16318, 6350, 2286, 836, 330, 108, 24, 12, 31980, 12252
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OFFSET

0,4


COMMENTS

For definitions, references and links related to complete rulers see A103294.
The values for n=208213 are 22,0,0,0,4,4 according to Arch D. Robison. The values for 199207 are not yet known.  Peter Luschny, Feb 20 2014, Jun 28 2019
Zero values at 135, 136, 149, 150, 151, 164, 165, 166, 179, 180, 181, 195, 196, 209, 210, 211.  Ed Pegg Jr, Jun 23 2019 [These values were found by Arch D. Robison, see links. Peter Luschny, Jun 28 2019]


LINKS

Peter Luschny (0..123) and Arch D. Robison (124..198), Table of n, a(n) for n = 0..198
Peter Luschny, Perfect and Optimal Rulers.
Arch D. Robison, Parallel Computation of Sparse Rulers, Jan 14 2014.
Index entries for sequences related to perfect rulers.


FORMULA

a(n) = T(n, A103298(n)) where the triangle T is described by A103294.


EXAMPLE

a(5)=4 counts the perfect rulers with length 5, {[0,1,3,5],[0,2,4,5],[0,1,2,5],[0,3,4,5]}.


CROSSREFS

Cf. A004137 (Maximal number of edges in a graceful graph on n nodes).
Cf. A103301, A103297, A103298.
Sequence in context: A220335 A117009 A204842 * A305402 A213394 A237981
Adjacent sequences: A103297 A103298 A103299 * A103301 A103302 A103303


KEYWORD

nonn,nice


AUTHOR

Peter Luschny Feb 28 2005


STATUS

approved



