A090636 Trajectory of 15 under the map k -> A003415(k) (taking the arithmetic derivative).

15, 8, 12, 16, 32, 80, 176, 368, 752, 1520, 3424, 8592, 20096, 70464, 235072, 705280, 3023616, 13223680, 55540736, 278539264, 1392697344, 9541095424, 58609614848, 410267320320, 3397142953984, 24143851798528, 176071227916288, 1232666139967488

Offset: 1

Author

N. J. A. Sloane, Dec 14 2003

Keywords

• nonn

Programs

Haskell

a090636 n = a090636_list !! (n-1)
a090636_list = iterate a003415 15  -- Reinhard Zumkeller, Apr 29 2012

PARI

A090636(n,a=15)={if(n<0, vector(-n,n, if(n>1, a=A003415(a), a)), for(n=2,n, a=A003415(a)); a)}  \\ For n<0 return the vector a[1..-n]. - M. F. Hasler, Nov 27 2019

Formula

a(n) = A129150(n-2) for n>1. - Reinhard Zumkeller, Apr 01 2007

Extensions

More explicit name from M. F. Hasler, Nov 27 2019