This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A039690 #21 Sep 17 2024 23:36:33
%S A039690 1,2,5,10,20,25,50,100,125,200,250,500,1000,1250,2000,2500,5000,10000,
%T A039690 12500,20000,25000,50000,100000,125000,200000,250000,500000,1000000,
%U A039690 1250000,2000000,2500000,5000000,10000000,12500000,20000000,25000000
%N A039690 Ambitious numbers: numbers n with the property that if a number ends in n then it is divisible by n.
%C A039690 Number whose 10's complement (A089186) is a multiple of it. 125 is a member as its 10's complement is 1000-125 = 875 = 125*7. - _Amarnath Murthy_, Mar 08 2002
%D A039690 P. J. Davis and R. Hersh, The Mathematical Experience, Birkhäuser, Boston and Basel, 1981; see pp. 293-298.
%H A039690 Problem of the week, <a href="http://mathforum.org/wagon">Web site</a> - problem 881
%H A039690 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,10).
%F A039690 Consists of the numbers 1, 2, 5, 25 or 125 times a power of 10.
%F A039690 a(n) = 10*a(n-5). - _Wesley Ivan Hurt_, May 03 2023
%e A039690 If a number ends in 2 then it is even and so is divisible by 2, so 2 is in the sequence.
%t A039690 LinearRecurrence[{0,0,0,0,10},{1,2,5,10,20,25,50,100,125},40] (* _Harvey P. Dale_, Sep 08 2018 *)
%Y A039690 Cf. A039690, A089186.
%K A039690 nonn,base,easy
%O A039690 1,2
%A A039690 _Erich Friedman_
%E A039690 Entry revised by _N. J. A. Sloane_, Aug 03 2004