login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A181721 The smallest number k such that the product k*n contains digit-reverse(n) as a substring. 3
1, 1, 1, 1, 1, 1, 1, 1, 1, 101, 1, 18, 24, 101, 34, 101, 42, 45, 48, 51, 6, 1, 14, 101, 21, 24, 27, 65, 32, 101, 23, 72, 1, 101, 101, 101, 29, 22, 24, 26, 28, 22, 8, 1, 12, 14, 42, 8, 6, 21, 3, 49, 67, 27, 1, 101, 75, 32, 5, 51 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,10

COMMENTS

Here, the digit-reverse operation is defined to preserve trailing zeros: for n=10, digit-reverse(n) = 01 which is a substring of 101*10=1010, so a(10)=101. - R. J. Mathar, Nov 17 2010

LINKS

Table of n, a(n) for n=1..60.

FORMULA

a(n) = A181720(n)/n. - Michel Marcus, Aug 12 2015

MAPLE

A181721 := proc(n) nrev := ListTools[Reverse](convert(n, base, 10)) ; for k from 1 do  dgskn := convert(k*n, base, 10) ; if verify(nrev, dgskn, sublist) then  return k; end if; end do: end proc:

seq(A181721(n), n=1..80) ; # R. J. Mathar, Nov 17 2010

CROSSREFS

Cf. A181720.

Sequence in context: A168588 A266323 A280372 * A277917 A281103 A164866

Adjacent sequences:  A181718 A181719 A181720 * A181722 A181723 A181724

KEYWORD

nonn,base

AUTHOR

Claudio Meller, Nov 17 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 5 00:21 EST 2021. Contains 349530 sequences. (Running on oeis4.)