A201462 - OEIS

A201462

Numbers that are not coprime to their 9's complement.

3, 6, 9, 11, 12, 15, 18, 21, 22, 24, 27, 30, 33, 36, 39, 42, 44, 45, 48, 51, 54, 55, 57, 60, 63, 66, 69, 72, 75, 77, 78, 81, 84, 87, 88, 90, 93, 96, 99, 102, 105, 108, 111, 114, 117, 120, 123, 126, 129, 132, 135, 138, 141, 144, 147, 148, 150, 153, 156, 159

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

All multiples of 3 are in this sequence. Multiples of 11 are in this sequence if they have an even number of digits or if they are also multiples of 3.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

EXAMPLE

22 is in the sequence because its 9's complement is 77 and gcd(22, 77) = 11 > 1.

MATHEMATICA

(* First run the program for A061601 to define nineComplement *) Select[Range[200], GCD[#, nineComplement[#]] > 1 &]

PROG

(Magma) [n: n in [3..159] | Gcd(10^#Intseq(n)-1, n) gt 1]; // Bruno Berselli, Dec 02 2011

(Haskell)

a201462 n = a201462_list !! (n-1)

a201462_list = [x | x <- [1..], gcd x (a061601 x) > 1]

-- Reinhard Zumkeller, Dec 03 2011