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N=>eval('for(k=0,n=1;n<=N;n++k=n=0;n++<N;)for(c=e=N%n||n;c<=e+N-n;k+=c*c++n;);k'k+=c*c++')
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-2 by Polichinelle.
Iteratively calculates sum, which is shorter than direct calculation.
N=>eval('for(k=0,n=1;n<=N;n++)for(c=e=N%n||n;c<=e+N-n;k+=c*c++);k')
Try it online!
N=>eval('for(k=n=0;n++<N;)for(c=e=N%n||n;c<=e+N-n;)k+=c*c++')
N=>eval('for(k=n=0;n<N;c=N%++n||n,d=c+N-nk=0,k+=d*-~d*(d-~dn=1;n<=N;n++)-~-c*c*for(c+cc=e=N%n||n;c<=e+N-1)n;k+=c*c++);k/6';k')
-1 by @KevinCruijssenTry it online!
DirectlyIteratively calculates the sum for each n, ratherwhich is shorter than iteratively doing sodirect calculation.
n
N=>eval('for(k=n=0;n<N;c=N%++n||n,d=c+N-n,k+=d*-~d*(d-~d)-~-c*c*(c+c-1));k/6')
-1 by @KevinCruijssen
Directly calculates the sum for each n, rather than iteratively doing so.
N=>eval('for(k=n=0;n<N;c=N%++n||n,d=c+N-n,k+=d*-~d*(d+d+1d-~d)-~-c*c*(c+c-1));k/6')
N=>eval('for(k=n=0;n<N;c=N%++n||n,d=c+N-n,k+=d*-~d*(d+d+1)-~-c*c*(c+c-1));k/6')
