A068667 a(1) = 7; a(n) = smallest palindromic multiple of a(n-1).

7, 77, 616, 6776, 88088, 616616, 232464232, 21154245112, 232696696232, 21175399357112, 21154245133154245112, 232696696464696696232, 21175399378287399357112, 63386501441764911946714410568336

Offset

1,1

Links

Table of n, a(n) for n=1..14.

Mathematica

a[1] = 7; 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, 14}]
NestList[Module[{k=2}, While[!PalindromeQ[k #], k++]; k #]&, 7, 10] (* The program generates the first 11 terms of the sequence. *) (* Harvey P. Dale, Feb 07 2025 *)

Crossrefs

Cf. A068664 (from a(6) on) and this sequence (from a(3) on) coincide.

Cf. A068664, A068665, A068666, A068668, A070069, A068971, A068972, A068973, A068974.

Sequence in context: A352995 A213261 A268958 * A261741 A228414 A043042

Adjacent sequences: A068664 A068665 A068666 * A068668 A068669 A068670

Keyword

base,nonn

Author

Amarnath Murthy, Mar 01 2002

Extensions

Last two terms from David W. Wilson, Sascha Kurz and edited by Patrick De Geest, Mar 30 2002

Status

approved