A103301 - OEIS

A103301

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

1, 1, 3, 9, 24, 88, 254, 1064, 1644, 3382, 4156, 8022, 26264, 52012, 25434, 8506, 5632, 6224, 12330, 34224, 108854, 103156, 75992, 86560, 69084

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

COMMENTS

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

LINKS

F. Schwartau, Y. Schröder, L. Wolf and J. Schoebel, MRLA search results and source code, Nov 6 2020.

FORMULA

a(n) = Sum_{i=A004137(n)+1..A004137(n+1)} A103300(i), n>=1.

EXAMPLE

a(3)=9 counts the perfect rulers with 3 segments, {[0,1,2,4],[0,2,3,4], [0,1,3,4],[0,1,3,5],[0,2,4,5],[0,1,2,5],[0,3,4,5],[0,1,4,6],[0,2,5,6]}.

CROSSREFS

Cf. A103300, A103297, A103296 (Complete rulers with n segments), A103299 (Optimal rulers with n segments).

KEYWORD

nonn,hard

AUTHOR

EXTENSIONS

Terms a(19)-a(24) found by exhaustive search by Fabian Schwartau, Yannic Schröder, Lars Wolf, Joerg Schoebel, Feb 23 2021

STATUS

approved