%I #12 Feb 24 2021 08:15:32
%S 1,1,2,3,3,4,4,6,6,7,7,7,8,10,11,11,11,11,11,13,14,15,15,16,14,19
%N Number of different lengths that perfect rulers with n segments can have.
%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) = A004137(n+1) - A004137(n) for n>= 1.
%e a(5)=4 because a perfect ruler with 5 segments may have the length 10, 11, 12 or 13.
%Y Cf. A103298.
%K nonn,hard
%O 0,3
%A _Peter Luschny_, Feb 28 2005
%E Term a(19) corrected and terms a(20)-a(25) added by Fabian Schwartau, _Yannic Schröder_, Lars Wolf, Joerg Schoebel, Feb 23 2021