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#!/usr/local/src/bin/calc/calc -q -f
/*
* mersenne - print the value of a mersenne number
*
* Copyright (C) 1999-2007,2014,2019,2021 Landon Curt Noll
*
* Calc is open software; you can redistribute it and/or modify it under
* the terms of the version 2.1 of the GNU Lesser General Public License
* as published by the Free Software Foundation.
*
* Calc 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 Lesser General
* Public License for more details.
*
* A copy of version 2.1 of the GNU Lesser General Public License is
* distributed with calc under the filename COPYING-LGPL. You should have
* received a copy with calc; if not, write to Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* Under source code control: 1999/11/30 00:09:01;
* File existed as early as: 1999
*
* chongo <was here> /\oo/\ http://www.isthe.com/chongo/
* Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
*
* usage:
* mersenne exp
*/
/*
* parse args
*/
argc = argv();
stderr = files(2);
program = argv(0);
if (argc != 2) {
/* we include the name of this script in the error message */
fprintf(stderr, "usage: %s exp\n", program);
abort "wrong number of args";
}
n = eval(argv(1));
if (!isint(n) || n <= 0) {
quit "Argument to be a positive integer";
}
/*
* print the decimal value of 2^n-1
*/
print "2^": n : "-1 =", 2^n-1;
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