123456789101112131415161718192021222324252627282930 |
- #!/usr/bin/ruby
- # Daniel "Trizen" Șuteu
- # License: GPLv3
- # Date: 12 December 2016
- # https://github.com/trizen
- # An efficient verification for an even perfect number.
- func is_even_perfect(n) {
- var v = valuation(n, 2) || return false
- var m = 1+(n >> v)
- (m & (m-1)).is_zero || return false
- (m >> (v+1)).is_one || return false
- is_mersenne_prime(v+1)
- }
- say is_even_perfect(191561942608236107294793378084303638130997321548169216) # true
- say is_even_perfect(191561942608236107294793378084303638130997321548169214) # false
- say is_even_perfect(191561942608236107294793378084303638130997321548169218) # false
- say is_even_perfect(14474011154664524427946373126085988481573677491474835889066354349131199152128) # true
- # A much larger perfect number
- say is_even_perfect(141053783706712069063207958086063189881486743514715667838838675999954867742652380114104193329037690251561950568709829327164087724366370087116731268159313652487450652439805877296207297446723295166658228846926807786652870188920867879451478364569313922060370695064736073572378695176473055266826253284886383715072974324463835300053138429460296575143368065570759537328128)
- # Search test
- for n in (1..10000) {
- is_even_perfect(n) && say n
- }
|