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 A087471 #8 Dec 05 2014 17:52:55
%S A087471 1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,2,4,6,8,0,2,4,6,8,0,3,6,9,2,
%T A087471 5,8,2,8,4,0,4,8,2,6,0,8,6,6,8,0,5,0,5,0,0,0,5,0,0,0,6,2,8,8,0,8,8,6,
%U A087471 0,0,7,4,2,6,5,8,8,0,8,0,8,6,8,6,0,6,0,8,4,0,9,8,4,8,0,0,8,4,8,0,0,0,0,0,0
%N A087471 Final digit resulting from iterations of the product of the two numbers formed from the alternating digits of n.
%C A087471 A087472(n) gives the number of iterations required for Murthy's function, f(n), to reach a single digit. A087473(n) gives the smallest number that requires n iterations of Murthy's function to reach a single digit. The n-th row of triangle A087474 gives the n successive iterations of Murthy's function on A087473(n).
%C A087471 Apart from the undefined a(0), the sequence differs from A031347 first at n=121. [From _R. J. Mathar_, Sep 11 2008]
%H A087471 Harvey P. Dale, <a href="/A087471/b087471.txt">Table of n, a(n) for n = 1..1000</a>
%F A087471 a(n) = a(f(n)), where f(n) is Murthy's function: f(1234)=13*24=312, f(12345)=135*24=3240, f(123456)=135*246=33210.
%e A087471 a(1234) = a(13*24) = a(312) = a(32*1) = a(32) = a(3*2) = 6.
%t A087471 Table[NestWhile[With[{idn=IntegerDigits[#]},FromDigits[Take[idn,{1,-1,2}]] FromDigits[Take[idn,{2,-1,2}]]]&,n,#>9&],{n,110}] (* _Harvey P. Dale_, Dec 05 2014 *)
%Y A087471 Cf. A087472, A087473, A087474.
%K A087471 nonn,base
%O A087471 1,2
%A A087471 _Amarnath Murthy_ and _Paul D. Hanna_, Sep 11 2003