Strange unique prime triplets: Difference between revisions
→{{header|Prolog}}
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=={{header|Prolog}}==
<syntaxhighlight lang="prolog">
primes(2, Limit):- 2 =< Limit.
primes(N, Limit):-
between(3, Limit, N),
N /\ 1 > 0, % odd
M is floor(sqrt(N)) - 1, % reverse 2*I+1
Max is M div 2,
forall(between(1, Max, I), N mod (2*I+1) > 0).
primeComb(N, List, Comb):-
comb(N, List, Comb),
sumlist(Comb, Sum),
primes(Sum, inf).
comb(0, _, []).
comb(N, [X|T], [X|Comb]):-
N > 0,
N1 is N - 1,
comb(N1, T, Comb).
comb(N, [_|T], Comb):-
N > 0,
comb(N, T, Comb).
tripletList(Limit, List, Len):-
findall(N, primes(N, Limit), PrimeList),
findall(Comb, primeComb(3, PrimeList, Comb), List),
length(List, Len).
showList([]).
showList([[I, J, K]|TList]):-
Sum is I + J + K,
writef('%3r +%3r +%3r =%3r\n', [I, J, K, Sum]),
showList(TList).
run([]).
run([Limit|TLimits]):-
tripletList(Limit, List, Len),
( Limit < 50
-> List1 = List
; List1 = []
),
showList(List1),
writef('number of prime Triplets up to%5r is%7r\n', [Limit, Len]),
run(TLimits).
do:- run([30, 1000]).
</syntaxhighlight>
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