OFFSET
1,1
COMMENTS
Prime elements of A181862.
Contains prime repunits A004022 as a subsequence.
a(5) > 1.4*10^7. - Giovanni Resta, Sep 18 2018
From Jason Yuen, Mar 25 2024: (Start)
For all x>log_10(p), 1+A007953(p-(10^x mod p)) >= A007953(p). This follows from the fact that 10^x+p-(10^x mod p) is a multiple of p.
a(5) > 2*10^11. See a181863_2e11.txt for more details. (End)
LINKS
Trevor Clokie, Thomas F. Lidbetter, Antonio Molina Lovett, Jeffrey Shallit, and Leon Witzman, Computational Aspects of Sturdy and Flimsy Numbers, Theoretical Computer Science, Vol. 927 (2022), pp. 65-86; arXiv preprint, arXiv:2002.02731 [cs.DS], 2020.
Jason Yuen, a181863_2e11.txt. This file shows that a(5) > 2*10^11.
CROSSREFS
KEYWORD
nonn,base,more,hard
AUTHOR
Max Alekseyev, Nov 14 2010
STATUS
approved