OFFSET
0,2
COMMENTS
The best known upper bounds for a(9-15) are 22, 25, 29, 33, 37, 41, 45. See attached file for the corresponding rulers. - Dmitry Kamenetsky, Mar 09 2018
LINKS
Dmitry Kamenetsky, Upper bounds and their rulers for a(9-15)
Carlos Rivera, The Prime Puzzles & Problems Connection: Puzzle 172.
Carlos Rivera, The Prime Puzzles & Problems Connection: Puzzle 914.
EXAMPLE
a(7)=15: there are 7 primes (2, 3, 5, 7, 11, 13, 17) and 8 ones. These rulers can generate every distance between 1 and 66, inclusive. There are two such rulers: 1.1.1.1.11.1.1.2.13.7.17.1.3.5.1 and 1.1.1.1.11.2.1.1.13.7.17.1.5.3.1
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Ray G. Opao, Jul 29 2004
STATUS
approved