cp's OEIS Frontend

A078268 Smallest integer which is an integer multiple of the number N obtained by placing the string "n" after a decimal point.

%I A078268 #25 May 01 2019 05:43:16
%S A078268 1,1,3,2,1,3,7,4,9,1,11,3,13,7,3,4,17,9,19,1,21,11,23,6,1,13,27,7,29,
%T A078268 3,31,8,33,17,7,9,37,19,39,2,41,21,43,11,9,23,47,12,49,1,51,13,53,27,
%U A078268 11,14,57,29,59,3,61,31,63,16,13,33,67,17,69,7,71,18,73,37,3,19,77,39,79
%N A078268 Smallest integer which is an integer multiple of the number N obtained by placing the string "n" after a decimal point.
%C A078268 Numerator of n/10^k, where k is the number of digits in n. - _Dean Hickerson_, Mar 21 2003
%C A078268 a(p) = p if p is a prime other than 2 and 5.
%C A078268 Smallest integer m such that the concatenation of decimal representations of m and n is a multiple of n. - _Reinhard Zumkeller_, Mar 19 2003
%C A078268 a(n) = numerator of fraction a/b, where gcd(a, b) = 1, such that its decimal representation has the form 0.(n). Denominators in A078267: 10, 5, 10, 5, 2, 5, 10, 5, 10, 10, 100, ... Example: a(6) = 3; 3/5 = 0.6. - _Jaroslav Krizek_, Feb 05 2010
%C A078268 a(n) = n iff gcd(n,10) = 1. - _Robert Israel_, Jul 25 2014
%H A078268 Harvey P. Dale, <a href="/A078268/b078268.txt">Table of n, a(n) for n = 1..1000</a>
%F A078268 a(n) = n *A078267(n)/10^A055642(n). - _Jaroslav Krizek_, Feb 05 2010
%F A078268 a(n) = n/A068822(n). - _L. Edson Jeffery_, Jul 25 2014
%e A078268 a(40)=2 since writing 40 after the decimal point gives 0.40 and 2 is the smallest integer multiple of 0.4.
%p A078268 a:= n -> numer(n/10^(1+ilog10(n))):
%p A078268 seq(a(n),n=1..100); # _Robert Israel_, Jul 25 2014
%t A078268 si[n_]:=Module[{c=n/10^IntegerLength[n],m=1},While[!IntegerQ[c*m],m++]; c*m]; Array[si,80] (* _Harvey P. Dale_, Apr 06 2013 *)
%t A078268 Table[n/GCD[n, 10^(1 + Floor[Log10[n]])], {n, 79}] (* _L. Edson Jeffery_, Jul 25 2014 *)
%o A078268 (PARI) a(n) = numerator(n/10^(#Str(n))); \\ _Michel Marcus_, Mar 31 2019
%Y A078268 Cf. A078267.
%K A078268 base,frac,nonn
%O A078268 1,3
%A A078268 _Amarnath Murthy_, Nov 24 2002
%E A078268 Edited and extended by _Henry Bottomley_, Dec 08 2002
%E A078268 Incorrect formula removed by _Jaroslav Krizek_, Feb 05 2010