

A109848


Highest common factor of n and its 9's complement.


2



1, 1, 3, 1, 1, 3, 1, 1, 9, 1, 11, 3, 1, 1, 3, 1, 1, 9, 1, 1, 3, 11, 1, 3, 1, 1, 9, 1, 1, 3, 1, 1, 33, 1, 1, 9, 1, 1, 3, 1, 1, 3, 1, 11, 9, 1, 1, 3, 1, 1, 3, 1, 1, 9, 11, 1, 3, 1, 1, 3, 1, 1, 9, 1, 1, 33, 1, 1, 3, 1, 1, 9, 1, 1, 3, 1, 11, 3, 1, 1, 9, 1, 1, 3, 1, 1, 3, 11, 1, 9, 1, 1, 3, 1, 1, 3, 1, 1, 99, 1, 1, 3
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,3


LINKS

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


EXAMPLE

a(55)=11 because the 9's complement of 55 is 99  55 = 44 and the greatest common divisor of 44 and 55 is 11.


MAPLE

digs := proc(inp::integer) local resul, shiftinp : resul := 1 : shiftinp := iquo(inp, 10) : while shiftinp > 0 do resul := resul+1 : shiftinp := iquo(shiftinp, 10) : od : RETURN(resul) : end: nin := proc(inp::integer) RETURN(10^digs(inp)1inp) : end : for n from 1 to 80 do comp := nin(n) ; #print(n, comp, gcd(n, comp)) ; printf("%d, ", gcd(n, comp)) ; od : # R. J. Mathar, Mar 27 2006


MATHEMATICA

hcf[n_]:=Module[{idn=IntegerDigits[n], c9}, c9=FromDigits[PadRight[{}, Length[idn], 9]idn]; GCD[n, c9]]; Array[hcf, 110] (* Harvey P. Dale, Dec 18 2012 *)


CROSSREFS

Cf. A109847, A084021.
Sequence in context: A038500 A091840 A083985 * A104146 A326405 A193179
Adjacent sequences: A109845 A109846 A109847 * A109849 A109850 A109851


KEYWORD

base,easy,nonn


AUTHOR

Amarnath Murthy, Jul 06 2005


EXTENSIONS

Corrected and extended by R. J. Mathar, Mar 27 2006
More terms from Joshua Zucker, May 03 2006


STATUS

approved



