16.04 – C Kernel in Jupyter Notebook not working

I set up Jupyter Notebook on a server and added a number of Kernels to be able to work not just in Python. All work apart from C. Even a simple test script like below does nothing.

#include <stdio.>
#include <math.h>

int main()
{
    printf("sqrt(67) = %f", sqrt(67));
    
    return 0;
}

To set up the C Kernel I followed the (simple) Manual instructions here.

The Manual Installation instructions here does not work.

Any guidelines appreciated.

Thanks.

……and a Happy, safe 2021 to all.