139808

Appears in sequences

• Numbers k such that sigma(phi(k)) is a prime.at n=40A062514
• Numbers k such that usigma(phi(k)) is a prime.at n=28A065875
• Numbers k such that phi(k) is a perfect 8th power.at n=17A078168
• a(n) = 121*n^2 - 2*n.at n=33A157040
• Binomial transform of A171372.at n=15A171373
• a(0)=-4; a(n+1) = 2*a(n) + period 4: repeat 6,1,2,5.at n=21A180343
• Number of (n+2) X 4 binary arrays with each 3 X 3 subblock having rows and columns in lexicographically nondecreasing order.at n=36A184541
• Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 529", based on the 5-celled von Neumann neighborhood.at n=17A282918
• Numbers h such that 2^phi(h) == phi(h) (mod h).at n=28A292544