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URL: https://oeis.org/A231472

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A231472
Largest integer less than 12 and coprime to n.
1
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 9, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 9, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 9, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 7, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 10
OFFSET
1,1
COMMENTS
Values in this sequence are 1, 5, 7, 8, 9, 10, and 11; the average value is 3569/330 = 10.81515.... - Charles R Greathouse IV, Aug 19 2016
LINKS
EXAMPLE
a(1..10)=11 because this is the largest integer less than 12 and it is coprime to n=1,...,10.
a(11)=10 because 11 is not coprime to 11 but 10 is.
a(22)=9 because 11 and 10 are not coprime to 22=2*11.
a(2310)=1 because 2310=2*3*5*7*11 is not coprime to any number n>1, n<12.
MATHEMATICA
Table[SelectFirst[Range[11, 1, -1], CoprimeQ[#, n]&], {n, 80}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 02 2018 *)
PROG
(PARI) a(n, m=12)=for(k=1, m, gcd(n, m-k)==1&&return(m-k))
CROSSREFS
Cf. A231471 (analog for 11), A231470 (analog for 10), A231155.
Sequence in context: A337241 A045538 A084066 * A319150 A112122 A290856
KEYWORD
nonn,easy
AUTHOR
M. F. Hasler, Nov 09 2013
STATUS
approved