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 A187844 #9 Jan 29 2014 04:03:55 %S A187844 0,-1,-2,-3,-4,-5,-6,-7,-8,-9,0,1,2,3,4,5,6,7,8,9,0,2,4,6,8,10,12,14, %T A187844 16,18,0,3,6,9,12,15,18,21,24,27,0,4,8,12,16,20,24,28,32,36,0,5,10,15, %U A187844 20,25,30,35,40,45,0,6,12,18,24,30,36,42,48,54,0,7,14,21,28,35,42,49,56,63,0,8,16,24,32,40,48,56,64 %N A187844 Product of negated digits of n. %C A187844 a(n) = A007954(n) * (-1)^A055642(n). %H A187844 Reinhard Zumkeller, <a href="/A187844/b187844.txt">Table of n, a(n) for n = 0..25000</a> %e A187844 a(289) = (-2) * (-8) * (-9) = -144; %e A187844 a(2891) = (-2) * (-8) * (-9) * (-1) = 144. %o A187844 (Haskell) %o A187844 import Data.Char (digitToInt) %o A187844 a187844 n = product $ map (negate . fromIntegral . digitToInt) $ show n %Y A187844 Cf. A187845 (partial sums). %K A187844 sign,base,look %O A187844 0,3 %A A187844 _Reinhard Zumkeller_, Mar 14 2011