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

Author

Amarnath Murthy, Jun 28 2001

Keywords

• nonn
• base
• easy

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

Examples

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

Crossrefs

Cf. A062884, A062885.

Programs

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);

Extensions

More terms from Sascha Kurz, Mar 25 2002