#include <R.h>
#include <Rinternals.h>
#include <Rmath.h>

SEXP ab(SEXP Ra, SEXP Rb){
  int i, a, b;
  SEXP Rval;
  Ra = coerceVector(Ra, INTSXP);
  Rb = coerceVector(Rb, INTSXP);
  a = INTEGER(Ra)[0];
  b = INTEGER(Rb)[0];
  PROTECT(Rval = allocVector(INTSXP, b - a + 1));
  for (i = a; i <= b; i++)
    INTEGER(Rval)[i - a] = i;
  UNPROTECT(1);
  return Rval;
}