Anonymous user
Perfect numbers: Difference between revisions
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→{{header|PARI/GP}}: lang tags
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=={{header|PARI/GP}}==
Uses built-in method. Faster tests would use the LL test for evens and myriad results on OPNs otherwise.
<lang parigp>isPerfect(n)=sigma(n,-1)==2</lang>
Show perfect numbers
<lang parigp>forprime(p=2, 2281,
if(isprime(2^p-1),
print(p"\t",(2^p-1)*2^(p-1))))</lang>
Faster with Lucas-Lehmer test
<lang parigp>p=2;n=3;n1=2;
while(p<2281,
if(isprime(p),
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</lang>
output
<
(2^3-1)2^(3-1)= 28
(2^5-1)2^(5-1)= 496
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(2^31-1)2^(31-1)= 2305843008139952128
(2^61-1)2^(61-1)= 2658455991569831744654692615953842176
(2^89-1)2^(89-1)= 191561942608236107294793378084303638130997321548169216</
=={{header|Perl}}==
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