A112392 Squares of the form 3*k - 2 where k is a semiprime.
16, 25, 64, 100, 169, 256, 361, 400, 529, 625, 676, 784, 961, 1156, 1444, 2116, 2209, 3136, 3721, 3844, 4096, 4489, 5041, 5929, 7744, 7921, 8281, 9604, 10000, 10201, 11236, 11449, 11881, 12100, 13456, 14641, 16129, 16384, 17161, 18496, 20164
Offset: 1
Keywords
Links
- Robert Israel, Table of n, a(n) for n = 1..1000
Programs
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Maple
select(issqr, map(t -> 3*t-2, select(t -> numtheory:-bigomega(t)=2,[$1..10000]))); # Robert Israel, May 25 2020
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Mathematica
Select[3#-2&/@Select[Range[7000],PrimeOmega[#]==2&],IntegerQ[ Sqrt[#]]&] (* Harvey P. Dale, Jun 22 2011 *)
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PARI
for(i=1,15000,if(bigomega(i)==2&&issquare(3*i-2),print1(3*i-2,","))) (Herrgesell)
Extensions
More terms from Lambert Herrgesell (zero815(AT)googlemail.com), Dec 12 2005
Comments