cp's OEIS Frontend

A091081 Numbers n which when converted to base 7, reversed and converted back to base 10 yield a number m such that n mod m = 0. Cases which are trivial or result in digit loss are excluded.

%I A091081 #6 Jun 08 2025 16:15:42
%S A091081 36,288,1800,2052,2304,12384,14400,16416,86472,88236,99072,100836,
%T A091081 115200,605088,619200,691776,705888,806688,4235400,4247748,4323600,
%U A091081 4335948,4840704,4853052,4928904,4941252,5534208,5647104,29647584,29746368,30254400,30353184
%N A091081 Numbers n which when converted to base 7, reversed and converted back to base 10 yield a number m such that n mod m = 0. Cases which are trivial or result in digit loss are excluded.
%C A091081 Trivial cases are those numbers which upon conversion result in a number which is palindromic (m = reverse(m)), or a palindrome plus trailing zeros such that m = reverse(m)*10^z where z=number of lost zeros. Nontrivial digit loss occurs when a converted number has trailing zeros that drop off when the number is reversed.
%H A091081 C. Seggelin, <a href="http://www.plastereddragon.com/maths/asortdiv.htm">Numbers Divisible by Digit Permutations</a>. [Broken link]
%e A091081 a(1) = 36 because: 36 in base 7 is 51; 51 reversed is 15; 15 converted back to base 10 is 12 and 36 mod 12 = 0.
%o A091081 (PARI) /* See A091077 and use PARI script with b=7 */
%Y A091081 Cf. A091077 (same in base 3), A091078 (base 4), A091079 (base 5), A091080 (base 6), A091082 (base 8), A091083 (base 9), A031877 (base 10).
%K A091081 base,nonn
%O A091081 1,1
%A A091081 _Chuck Seggelin_, Dec 18 2003
%E A091081 More terms from _Michel Marcus_, Oct 10 2014