A187844 Product of negated digits of n.

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, 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, 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

Offset: 0

Author

Reinhard Zumkeller, Mar 14 2011

Keywords

• sign
• base
• look

Comments

a(n) = A007954(n) * (-1)^A055642(n).

Examples

			a(289) = (-2) * (-8) * (-9) = -144;
a(2891) = (-2) * (-8) * (-9) * (-1) = 144.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..25000

Crossrefs

Cf. A187845 (partial sums).

Programs

Haskell

import Data.Char (digitToInt)
a187844 n = product $ map (negate . fromIntegral . digitToInt) $ show n