A068665 a(1) = 3; a(n) = smallest palindromic multiple of a(n-1).

3, 6, 66, 858, 6006, 66066, 858858, 222444222, 444888444, 21354645312, 21375999957312, 211643775577346112, 211432343445544343234112, 21354666687999978666645312, 211432554877887788778455234112, 211221333755564778877465557333122112

Offset: 1

Author

Amarnath Murthy, Mar 01 2002

Keywords

• nonn
• base

Links

• Giovanni Resta, Table of n, a(n) for n = 1..19

Crossrefs

Cf. A068664, A068666, A068667, A068668, A070069, A068971, A068972, A068973, A068974, A083149.

Programs

Mathematica

a[1] = 3; a[n_] := a[n] = Block[{k = 2}, While[k*a[n - 1] != ToExpression[ StringReverse[ ToString[k*a[n - 1]]]], k++ ]; k*a[n - 1]]; Table[a[n], {n, 1, 16}]
nxt[n_]:=Module[{k=2},While[k*n!=IntegerReverse[k*n],k++];k*n]; NestList[ nxt,3,15] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 14 2016 *)

Extensions

More terms from David W. Wilson; edited by Patrick De Geest, Mar 30 2002

a(16) from Giovanni Resta, Sep 22 2019