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 A068090 #15 Jul 02 2025 19:35:28 %S A068090 1,2,3,4,5,6,8,9,10,12,14,15,18,20,24,25,30,35,36,39,40,45,50,60,72, %T A068090 75,80,90,100,120,125,144,150,180,200,204,225,240,250,300,360,375,400, %U A068090 450,500,507,540,585,600,624,625,675,702,720,750,780,800,804,864,900 %N A068090 Numbers n which divide the right concatenation of the first n even numbers. %e A068090 The right concatenation of the first six even numbers is 24681012 and 6 divides this number. So 6 is a member of the sequence. %p A068090 a := proc(n): if n=1 then RETURN(2) fi: 2*n+a(n-1)*10^(ceil(log[10](2*n+.01))) end: for n from 1 to 1000 do if a(n) mod n = 0 then printf(`%d,`,n) fi; od: %t A068090 concat[n_]:=FromDigits[Flatten[IntegerDigits/@Range[2,2n,2]]]; Select[ Range[700],Divisible[concat[#],#]&] (* _Harvey P. Dale_, Nov 02 2011 *) %Y A068090 Cf. A029455. %K A068090 base,easy,nonn %O A068090 1,2 %A A068090 _Amarnath Murthy_, Feb 19 2002 %E A068090 Edited and extended by _James Sellers_, Feb 20 2002 %E A068090 Offset corrected by _Sean A. Irvine_, Jan 25 2024