Problem solved! Fortran 2008 has bessel_jn(n, x) intrinsic.
http://fortranwiki.org/fortran/show/bessel_jn
I compiled my .f95 using this function and of course setting the standard as 2008, i.e.,
gfortran -c -std=f2008 .\testf2008.f95
and then
gfortran -o a .\testf2008.o
Result...