# Computed 2018-09-03 in GP/PARI CALCULATOR Version 2.9.4 (released) amd64 running linux (x86-64/GMP-6.1.2 kernel) 64-bit version, compiled: Dec 19 2017, gcc version 7.3.0 (Ubuntu 7.3.0-1ubuntu1), threading engine: pthread # with the following program: # # up_to = (2^16)+1; # A055653(n) = sumdiv(n, d, if(gcd(n/d, d)==1, eulerphi(d))); \\ From A055653 # DirSqrt(v) = {my(n=#v, u=vector(n)); u[1]=1; for(n=2, n, u[n]=(v[n]/v[1] - sumdiv(n, d, if(d>1&&d