A068666 a(1) = 5; a(n) = smallest palindromic multiple of a(n-1).

5, 55, 5005, 55055, 50155105, 5065665605, 50155155155105, 5464353998993534645, 541025148469303964841520145, 513016415223221833242338122322514610315

Offset

1,1

Links

Table of n, a(n) for n=1..10.

Mathematica

a[1] = 5; 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, 9}]
spm[n_]:=Module[{k=2}, While[!PalindromeQ[k*n], k++]; k*n]; NestList[spm, 5, 10] (* Harvey P. Dale, Nov 10 2022 *)

Crossrefs

Cf. A068664, A068665, A068667, A068668, A070069, A068971, A068972, A068973, A068974.

Sequence in context: A105715 A111821 A275546 * A082780 A063855 A081785

Adjacent sequences: A068663 A068664 A068665 * A068667 A068668 A068669

Keyword

base,nonn,more

Author

Amarnath Murthy, Mar 01 2002

Extensions

Corrected and extended by David W. Wilson and Patrick De Geest, Mar 30 2002

a(10) from John Gustaf Stebbins, Sep 17 2008

Status

approved