164480

Appears in sequences

• Numbers k such that sigma(phi(k)) is a prime.at n=42A062514
• Numbers k such that usigma(phi(k)) is a prime.at n=30A065875
• Numbers k such that phi(k) is a perfect 8th power.at n=19A078168
• Janet periodic table of the elements and structured hexagonal diamond numbers. a(n) = A166911(2*n) + A166911(2*n+1).at n=19A167471
• The number of idempotents in the Brauer monoid on [1..n].at n=8A227545
• Number of (n+1) X (2+1) 0..3 arrays with every 2 X 2 subblock summing to 3 6 or 9.at n=3A251294
• Number of (n+1)X(4+1) 0..3 arrays with every 2X2 subblock summing to 3 6 or 9.at n=1A251296
• T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with every 2X2 subblock summing to 3 6 or 9.at n=11A251300
• T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with every 2X2 subblock summing to 3 6 or 9.at n=13A251300
• Number of (n+2)X(4+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7.at n=7A251872
• Numbers n such that sigma(n) - 1 and sigma(phi(n)) are both primes.at n=24A270416
• E.g.f.: exp(x/(1-x^2))/sqrt(1-x^2).at n=8A277379
• Numbers h such that 2^phi(h) == phi(h) (mod h).at n=30A292544
• Number of nonisomorphic proper colorings of partition star graph using five colors.at n=59A297569