A110404 Least multiple of n which is a repeated reverse concatenation of digits of n where n == 1, 3, 7 or 9 (mod 10).

1, 3, 7, 9, 11, 313131, 7171717171717171, 919191919191919191, 121212, 3232323232323232323232, 727272, 9292929292929292929292929292, 131313131313131313131313131313, 33, 737373, 939393, 1414141414

Offset

1,2

Links

Table of n, a(n) for n=1..17.

Example

For 13 the term is 313131 as 313131 = 13*24087.

Mathematica

f[n_] := Block[{k = 1, id = Reverse[ IntegerDigits[n]]}, While[fd = FromDigits[ Flatten[ Table[id, {k}]]]; Mod[fd, n] != 0, k++ ]; fd]; lst = Select[ Range[1, 41, 2], Mod[ #, 5] != 0 &]; f /@ lst (* Robert G. Wilson v *)

Crossrefs

Cf. A110405.

Sequence in context: A114788 A085074 A175637 * A366529 A190366 A342699

Adjacent sequences: A110401 A110402 A110403 * A110405 A110406 A110407

Keyword

base,easy,nonn

Author

Amarnath Murthy, Jul 30 2005

Extensions

More terms from Robert G. Wilson v, Jul 30 2005

Status

approved