it should be like this.// the niumber iin the subscript being oin

paranthesis is what indicates that its a rising factorial:
'n➔when(n=0,1,else,x*F(n-1)*(∏α₍ₖ₎(k=1..p)/∏β₍ₖ₎(k=1..q))'

src/main/java/arb/functions/real/HypergeometricFunctionSequence.java

@@ -38,7 +38,7 @@ public static void main(String... args)
 
   public final Function<Integer, RealPolynomial> F;
 
-  public static final String                     Fdef = "n➔when(n=0,1,else,x*F(n-1)*(∏αₖ(k=1..p)/∏βₖ(k=1..q))";
+  public static final String                     Fdef = "n➔when(n=0,1,else,x*F(n-1)*(∏α₍ₖ₎(k=1..p)/∏β₍ₖ₎(k=1..q))";
 
   public HypergeometricFunctionSequence(int p, int q)
   {