A068664 - OEIS

%I #14 Oct 26 2019 02:07:02

%S 1,2,4,8,88,616,6776,88088,616616,232464232,21154245112,232696696232,

%T 21175399357112,21154245133154245112,232696696464696696232,

%U 21175399378287399357112,63386501441764911946714410568336

%N a(1) = 1, a(n) = smallest palindromic multiple of a(n-1).

%t a=1; Print[a]; For[n = 2, n <= 15, n++, {an = a; k = 2; str = ToString[k*an]; rstr = StringReverse[str]; While[str != rstr, {k = k + 1; str = ToString[k*an]; rstr = StringReverse[str]; If[k*an > 10^20, {Print["Too big"]; Abort[]}]}]; a := k*an; Print[k, " ", a];}]

%t spm[n_]:=Module[{k=2},While[!PalindromeQ[k*n],k++];k*n]; NestList[spm,1,15] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 02 2019 *)

%Y A068667 (from a(3) on) and this sequence (from a(6) on) coincide.

%Y Cf. A068665, A068666, A068667, A068668, A070069, A068971, A068972, A068973, A068974.

%K base,nonn

%O 1,2

%A _Amarnath Murthy_, Mar 01 2002

%E Extended and edited by _John W. Layman_, Mar 18 2002

%E Last two terms from _David W. Wilson_ and _Patrick De Geest_, Mar 30 2002