OFFSET
1,2
COMMENTS
If an integer is in this sequence, its 9's complement is in the sequence as well. No multiple of 3 is in this sequence. Multiples of 11 are in the sequence if they have an odd number of digits and they are not also multiples of 3.
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
EXAMPLE
25 is in the sequence because its 9's complement is 74 and gcd(25, 74) = 1.
MAPLE
with(numtheory): P:=proc(q) local k, n; for n from 1 to q do for k from 1 to q do
if type(((n-k)*10^(ilog10(n+k)+1)+n+k)/n, integer) then break; fi; od;
if k=n then print(n); fi; od; end: P(10^4); # Paolo P. Lava, Nov 03 2014
MATHEMATICA
(* First run the program for A061601 to define nineComplement *) Select[Range[100], GCD[#, nineComplement[#]] == 1 &]
PROG
(Magma) [n: n in [1..106] | Gcd(10^#Intseq(n)-1, n) eq 1]; // Bruno Berselli, Dec 02 2011
(Haskell)
a192817 n = a192817_list !! (n-1)
a192817_list = [x | x <- [1..], gcd x (a061601 x) == 1]
-- Reinhard Zumkeller, Dec 03 2011
CROSSREFS
KEYWORD
nonn,easy,base
AUTHOR
Alonso del Arte, Dec 01 2011
STATUS
approved