#! /usr/bin/env python
#
def padovan ( n ):

#*****************************************************************************80
#
## PADOVAN returns the first N values of the Padovan sequence.
#
#  Discussion:
#
#    The Padovan sequence has the initial values:
#
#      P(0) = 1
#      P(1) = 1
#      P(2) = 1
#
#    and subsequent entries are generated by the recurrence
#
#      P(I+1) = P(I-1) + P(I-2)
#
#  Example:
#
#    0   1
#    1   1
#    2   1
#    3   2
#    4   2
#    5   3
#    6   4
#    7   5
#    8   7
#    9   9
#   10  12
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license. 
#
#  Modified:
#
#    26 May 2015
#
#  Author:
#
#    John Burkardt
#
#  Reference:
#
#    Ian Stewart,
#    "A Neglected Number",
#    Scientific American, Volume 274, pages 102-102, June 1996.
#
#    Ian Stewart,
#    Math Hysteria,
#    Oxford, 2004.
#
#  Parameters:
#
#    Input, integer N, the number of terms.
#
#    Output, integer P(N), terms 0 though N-1 of the Perrin sequence.
#
  import numpy as np

  p = np.zeros ( n )

  if ( 1 <= n ):

    p[0] = 1

    if ( 2 <= n ):

      p[1] = 1

      if ( 3 <= n ):
 
        p[2] = 1

        for i in range ( 3, n ):
          p[i] = p[i-2] + p[i-3]

  return p

def padovan_test ( ):

#*****************************************************************************80
#
## PADOVAN_TEST tests PADOVAN.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    26 May 2015
#
#  Author:
#
#    John Burkardt
#
  import platform
  from i4vec_print import i4vec_print

  n = 10

  print ( '' )
  print ( 'PADOVAN_TEST' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  PADOVAN computes the Padovan numbers.' )

  p = padovan ( n );

  i4vec_print ( n, p, '  Initial Padovan sequence:' )
#
#  Terminate.
#
  print ( '' )
  print ( 'PADOVAN_TEST:' )
  print ( '  Normal end of execution.' )
  return

if ( __name__ == '__main__' ):
  from timestamp import timestamp
  timestamp ( )
  padovan_test ( )
  timestamp ( )