Math::NumSeq::Pronic -- pronic numbers
use Math::NumSeq::Pronic; my $seq = Math::NumSeq::Pronic->new; my ($i, $value) = $seq->next;
The pronic numbers i*(i+1), starting from i=0,
0, 2, 6, 12, 20, 30, ...
These are twice the triangular numbers, and half way between the perfect squares.
See "FUNCTIONS" in Math::NumSeq for behaviour common to all sequence classes.
$seq = Math::NumSeq::Pronic->new (key=>value,...)
Create and return a new sequence object.
$value = $seq->ith($i)
Return $i*($i+1).
$i*($i+1)
$bool = $seq->pred($value)
Return true if $value is a pronic number, ie. i*(i+1) for some i.
$value
$i = $seq->value_to_i_estimate($value)
Return an estimate of the i corresponding to $value. value=i*(i+1) is inverted by $i = int ((sqrt(4*$value + 1) - 1)/2).
$i = int ((sqrt(4*$value + 1) - 1)/2)
Math::NumSeq, Math::NumSeq::Squares, Math::NumSeq::Triangular
http://user42.tuxfamily.org/math-numseq/index.html
Copyright 2010, 2011, 2012 Kevin Ryde
Math-NumSeq is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.
Math-NumSeq is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with Math-NumSeq. If not, see <http://www.gnu.org/licenses/>.
To install Math::NumSeq, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Math::NumSeq
CPAN shell
perl -MCPAN -e shell install Math::NumSeq
For more information on module installation, please visit the detailed CPAN module installation guide.