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 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)-1-inp) : 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

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Last modified April 13 01:36 EDT 2021. Contains 342934 sequences. (Running on oeis4.)