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 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 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

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