A038570 Second derivative of n.

0, 0, 0, 0, 1, 0, 0, 0, 2, 3, 0, 1, 1, 0, 0, 0, 4, 5, 6, 7, 1, 0, 3, 2, 2, 3, 0, 1, 1, 0, 0, 0, 8, 9, 10, 11, 13, 12, 15, 14, 2, 3, 0, 1, 7, 6, 5, 4, 4, 5, 6, 7, 1, 0, 3, 2, 2, 3, 0, 1, 1, 0, 0, 0, 16, 17, 18, 19, 21, 20, 23, 22, 26, 27, 24, 25, 31, 30, 29, 28, 4, 5, 6, 7, 1, 0, 3, 2, 14, 15, 12

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy
• nice
• look

Comments

a(n) = A038554(A038554(n)). - Reinhard Zumkeller, Mar 06 2013

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A038554.

Programs

Haskell

a038570 = a038554 . fromIntegral . a038554
-- Reinhard Zumkeller, Mar 06 2013

Mathematica

dtn[ L_ ] := Fold[ 2#1+#2&, 0, L ]; f[ n_ ] := dtn[ Map[ Abs[ #[ [ 1 ] ]-#[ [ 2 ] ] ]&, Partition[ IntegerDigits[ n, 2 ], 2, 1 ] ] ]; Table[ f[ f[ n ] ], {n, 0, 120} ]

Extensions

More terms from Erich Friedman