++ed by:
Kevin Ryde
and 1 contributors

# NAME

Math::NumSeq::WoodallNumbers -- Woodall numbers i*2^i-1

# SYNOPSIS

`````` use Math::NumSeq::WoodallNumbers;
my \$seq = Math::NumSeq::WoodallNumbers->new;
my (\$i, \$value) = \$seq->next;``````

# DESCRIPTION

The Woodall numbers i*2^i-1 starting from i=1,

``    1, 7, 23, 63, 159, 383, 895, 2047, 4607, 10239, ...``

# FUNCTIONS

See "FUNCTIONS" in Math::NumSeq for behaviour common to all sequence classes.

`\$seq = Math::NumSeq::WoodallNumbers->new ()`

Create and return a new sequence object.

## Iterating

`\$seq->seek_to_i(\$i)`

Move the current sequence position to `\$i`. The next call to `next()` will return `\$i` and corresponding value.

## Random Access

`\$value = \$seq->ith(\$i)`

Return `\$i * 2**\$i - 1`.

`\$bool = \$seq->pred(\$value)`

Return true if `\$value` is a Woodall number, ie. is equal to i*2^i-1 for some i.

`\$i = \$seq->value_to_i_floor(\$value)`

Return the index i of `\$value` or of the next Woodall number below `\$value`.

`\$i = \$seq->value_to_i_estimate(\$value)`

Return an estimate of the i corresponding to `\$value`.

# FORMULAS

## Value to i Estimate

An easy over-estimate is l=log2(value), which reverses value=2^l. It can be reduced by the bit length of that l as i=l-log2(l) to get closer.

# HOME PAGE

http://user42.tuxfamily.org/math-numseq/index.html

# LICENSE

Copyright 2011, 2012, 2013, 2014 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/>.