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A193803 Length of perfect Wichmann rulers. 3
3, 6, 9, 12, 15, 18, 22, 29, 36, 43, 46, 50, 57, 64, 68, 71, 79, 90, 101, 108, 112, 123, 134, 138, 145, 153, 156, 168, 175, 183 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

R is a perfect Wichmann ruler iff R is a perfect ruler (for definition see A103294) and there exist two integers r>=0 and s>=0 such that the type of the difference representation of the ruler is [1*r, r+1, (2r+1)*r, (4r+3)*s, (2r+2)*(r+1), 1*r].

LINKS

Table of n, a(n) for n=1..30.

L. Egidi and G. Manzini, Spaced seeds design using perfect rulers, Tech. Rep. CS Department Universita del Piemonte Orientale, June 2011.

Peter Luschny, Perfect rulers

B. Wichmann, A note on restricted difference bases, J. Lond. Math. Soc. 38 (1963), 465-466.

EXAMPLE

[0, 1, 2, 5, 10, 15, 26, 37, 48, 54, 60, 66, 67, 68] is a perfect Wichmann ruler with length 68 of Wichmann type (2,3). By contrast [0, 1, 2, 8, 15, 16, 26, 36, 46, 56, 59, 63, 65, 68] is a perfect ruler with length 68 which is not a Wichmann ruler.

CROSSREFS

Cf. A004137, A193802.

Sequence in context: A292666 A028251 A194226 * A284601 A039004 A070021

Adjacent sequences:  A193800 A193801 A193802 * A193804 A193805 A193806

KEYWORD

nonn,hard,more

AUTHOR

Peter Luschny, Oct 22 2011

STATUS

approved

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Last modified October 15 04:33 EDT 2019. Contains 328026 sequences. (Running on oeis4.)