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Smallest nontrivial multiple of n ending in n. By nontrivial one means a(n) is not equal to n or concatenation of n with itself.
1

%I #5 Aug 23 2014 15:06:40

%S 21,12,63,24,15,36,147,48,189,110,2211,312,2613,714,315,416,3417,918,

%T 3819,120,4221,1122,4623,624,125,1326,5427,728,5829,330,6231,832,6633,

%U 1734,735,936,7437,1938,7839,240,8241,2142,8643,1144,945

%N Smallest nontrivial multiple of n ending in n. By nontrivial one means a(n) is not equal to n or concatenation of n with itself.

%p A083466 := proc(n)

%p ndgs := convert(n,base,10) ;

%p for k from 2 do

%p if k*n <> digcat2(n,n) then

%p kdgs := convert(k*n,base,10) ;

%p mtch := true ;

%p for i from 1 to nops(ndgs) do

%p if op(i,ndgs) <> op(i,kdgs) then

%p mtch := false;

%p break;

%p end if;

%p end do:

%p if mtch then

%p return k*n ;

%p end if;

%p end if;

%p end do:

%p end proc: # _R. J. Mathar_, Aug 23 2014

%K base,easy,nonn

%O 1,1

%A _Amarnath Murthy_ and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 02 2003

%E More terms from _R. J. Mathar_, Aug 23 2014