A231472 Largest integer less than 12 and coprime to n.

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

Harvey P. Dale, Table of n, a(n) for n = 1..1000

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

Adjacent sequences: A231469 A231470 A231471 * A231473 A231474 A231475

Keyword

nonn,easy

Author

M. F. Hasler, Nov 09 2013

Status

approved