cp's OEIS Frontend

A186943 Number of lunar divisors (in base 10) of the n-th number whose decimal expansion contains only 0's and 1's and begins and ends with a 1 (A099821(n)).

%I A186943 #19 Aug 06 2014 16:23:20
%S A186943 9,90,90,819,90,738,738,7461,90,738,819,6570,738,6732,6570,67968,90,
%T A186943 738,738,6570,738,6570,6732,59868,738,6732,6570,59868,6570,59868,
%U A186943 59868,619902,90,738,738,6570,819,6570,6570,59058,738,6570,7461,59058,6570,59868,59058,539550,738,6732,6570,59868,6570,59058,59868,538821,6570,59868,59058,538902,59058,538821,539550,5660208,90,738,738,6570,738,6570,6570
%N A186943 Number of lunar divisors (in base 10) of the n-th number whose decimal expansion contains only 0's and 1's and begins and ends with a 1 (A099821(n)).
%C A186943 Number of lunar divisors of A099821(n), that is, A087029(A099821(n))..
%H A186943 N. J. A. Sloane, <a href="/A186943/b186943.txt">Table of n, a(n) for n = 1..100</a>
%H A186943 D. Applegate, M. LeBrun and N. J. A. Sloane, <a href="http://arxiv.org/abs/1107.1130">Dismal Arithmetic</a> [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]
%H A186943 <a href="/index/Di#dismal">Index entries for sequences related to dismal (or lunar) arithmetic</a>
%e A186943 1 has 9 divisors: 1,2,3,4,5,6,7,8,9, so a(1)=9. 11 has 90 divisors, 1 through 9 and the numbers 11 through 99 that do not end in 0, so a(2)=90.
%Y A186943 Cf. A087029, A099821.
%K A186943 nonn,base
%O A186943 1,1
%A A186943 _N. J. A. Sloane_, Mar 01 2011