A181721 - OEIS

%I #13 Aug 12 2015 03:28:14

%S 1,1,1,1,1,1,1,1,1,101,1,18,24,101,34,101,42,45,48,51,6,1,14,101,21,

%T 24,27,65,32,101,23,72,1,101,101,101,29,22,24,26,28,22,8,1,12,14,42,8,

%U 6,21,3,49,67,27,1,101,75,32,5,51

%N The smallest number k such that the product k*n contains digit-reverse(n) as a substring.

%C Here, the digit-reverse operation is defined to preserve trailing zeros: for n=10, digit-reverse(n) = 01 which is a substring of 101*10=1010, so a(10)=101. - _R. J. Mathar_, Nov 17 2010

%F a(n) = A181720(n)/n. - _Michel Marcus_, Aug 12 2015

%p A181721 := proc(n) nrev := ListTools[Reverse](convert(n,base,10)) ; for k from 1 do  dgskn := convert(k*n,base,10) ; if verify(nrev,dgskn,sublist) then  return k; end if; end do: end proc:

%p seq(A181721(n),n=1..80) ; # _R. J. Mathar_, Nov 17 2010

%Y Cf. A181720.

%K nonn,base

%O 1,10

%A _Claudio Meller_, Nov 17 2010