# Computed 2018-07-03 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: # # A007947(n) = factorback(factorint(n)[, 1]); # f(n) = if(isprime(n),1,if(n%4,A007947(n),2*A007947(n))); # A144776(n) = if(n<2,0,my(x=f(n)); if(!isprime(n)&&(x>=n),0,sum(k=1,n-1,(f(k)