code: function ekurtosis( p ) {
  	if ( !( isNumber(p) && 0 <= p && p <= 1) ) {
  		return NaN;
  	}
  	return 6 + square( p ) / ( 1 - p );
  }
docs: EKURTOSIS // 
  FUNCTION ekurtosis( p )
  Computes the distribution ekurtosis for a geometric distribution with parameter p.
  
  @param {Number} p - success probability
  @returns {Number} distribution ekurtosis