A062887 Smallest multiple of 2n+1 with the property that its digits are odd and each digit is two less (mod 10) than the previous digit, or 0 if no such number exists.

1, 3, 5, 7, 9, 319, 975, 75, 7531, 19, 197531975319, 3197, 75, 5319, 319, 31, 3197531975319, 53197531975, 1975319, 975, 531975, 1975319753197, 19753197531975, 75319753197531, 319753197531975319, 753197531975319753

Offset

0,2

Comments

Conjecture: The only numbers n for which a(n)=0 are those for which 2*n+1 is divisible by 125. - Sean A. Irvine, Apr 14 2023

Links

Table of n, a(n) for n=0..25.

Example

a(7) = 975 = 13*75 has decreasing odd digits.

Maple

l := 0:for i from 1 to 35 do for j from 1 to 5 do a := 0:for h from 1 to i do a := 10*a+((2*j+1-2*h) mod 10):end do:l := l+1:q[l] := a:end do:end do:s := seq(q[ll], ll=1..l); for i from 1 to 65 do k := 1:while((s[k] mod (2*i-1))>0) do k := k+1:end do: w[i] := s[k]:end do:seq(w[j], j=1..65);

Crossrefs

Cf. A062884, A062885.

Sequence in context: A068061 A332970 A316492 * A062886 A319585 A133452

Adjacent sequences: A062884 A062885 A062886 * A062888 A062889 A062890

Keyword

nonn,base,easy

Author

Amarnath Murthy, Jun 28 2001

Extensions

More terms from Sascha Kurz, Mar 25 2002

Status

approved