OFFSET
1,1
COMMENTS
Periodic with period 210.
Motivated by A231155(n)=a(n)*(10^(n-1)-1)/9.
a(n) is in {1, 5, 7, 8, 9}. Average value is 253/30 = 8.433.... - Charles R Greathouse IV, Oct 13 2022
LINKS
EXAMPLE
a(210)=1 because 210=2*3*5*7 is not coprime to any number n>1, n<10.
PROG
(PARI) a(n)=for(k=1, 9, gcd(n, 10-k)==1&&return(10-k)))
(PARI) a(n)=n=n%210; (2456570291879305656378327950088507572292988734220585220471023291179171177166614 45448973642646595615830994341498146323777941833948520102560885856758200689935551 394284409822886865709103348710416026442401 \ 9^n)%9+1 \\ Charles R Greathouse IV, Oct 13 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
M. F. Hasler, Nov 09 2013
STATUS
approved