

A308766


Numbers n such that the minimal mark in a length n sparse ruler is round(sqrt(9+12*n)/2) + 1.


3



51, 59, 69, 113, 124, 125, 135, 136, 139, 149, 150, 151, 164, 165, 166, 179, 180, 181, 195, 196, 199, 209, 210, 211
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OFFSET

1,1


COMMENTS

Other sparse rulers in the range length 1 to 213 have round(sqrt(9+12*n)/2) minimal marks.
Minimal vertices in nedge graceful graph = minimal marks in length n sparse ruler.
Minimal marks can be derived from A004137 and using zerocount values in A103300.
Conjecture: Minimal marks n  round(sqrt(9+12*n)/2) is always 0 or 1.


LINKS

Table of n, a(n) for n=1..24.
P. Luschny, The Perfect Ruler Pyramid (1101)
P. Luschny, Perfect and Optimal Rulers


CROSSREFS

Cf. A046693, A004137, A103300, A103294.
Sequence in context: A095525 A045805 A031410 * A039387 A043210 A043990
Adjacent sequences: A308763 A308764 A308765 * A308767 A308768 A308769


KEYWORD

nonn,hard,more


AUTHOR

Ed Pegg Jr, Jun 23 2019


STATUS

approved



