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Number of optimal rulers with n segments (n>=0).
4

%I #18 Feb 24 2021 08:15:25

%S 1,1,2,2,4,6,12,4,6,2,2,4,12,4,2,2,2,2,4,2,2,2,2,2,4

%N Number of optimal rulers with n segments (n>=0).

%C For definitions, references and links related to complete rulers see A103294.

%H F. Schwartau, Y. Schröder, L. Wolf and J. Schoebel, <a href="https://dx.doi.org/10.21227/cd4b-nb07">MRLA search results and source code</a>, Nov 6 2020.

%H F. Schwartau, Y. Schröder, L. Wolf and J. Schoebel, <a href="https://doi.org/10.1109/OJAP.2020.3043541">Large Minimum Redundancy Linear Arrays: Systematic Search of Perfect and Optimal Rulers Exploiting Parallel Processing</a>, IEEE Open Journal of Antennas and Propagation, 2 (2021), 79-85.

%H <a href="/index/Per#perul">Index entries for sequences related to perfect rulers.</a>

%F a(n) = A103300(A004137(n+1)).

%e a(5)=6 counts the optimal rulers with 5 segments, {[0,1,6,9,11,13], [0,2,4,7,12,13], [0,1,4,5,11,13], [0,2,8,9,12,13], [0,1,2,6,10,13], [0,3,7,11,12,13]}.

%Y Cf. A103296 (Complete rulers with n segments), A103301 (Perfect rulers with n segments).

%K nonn,hard,more

%O 0,3

%A _Peter Luschny_, Feb 28 2005

%E Terms a(20)-a(24) proved by exhaustive search by Fabian Schwartau, _Yannic Schröder_, Lars Wolf, Joerg Schoebel, Feb 22 2021