%I #4 Mar 30 2012 17:22:35
%S 3,31,101,3823,2266366724843687556556015073508073201681
%N Prime coefficient of x^n in (x^3+x^2+x+1)^n for n in A104311.
%C a(6), which corresponds to n=649, is too large to include.
%t f=1; Do[f=Expand[f*(x^3+x^2+x+1)]; s=Coefficient[f, x, n]; If[PrimeQ[s], Print[{n, s}]], {n, 1000}]
%Y Cf. A005725 (quadrinomial coefficients), A104314 (nontrivial prime pentanomial coefficients).
%K nonn
%O 1,1
%A _T. D. Noe_, Mar 01 2005