(18A. Protagonist in Kerouac’s “On the Road”), MY BLUE  HEAVEN (27A. 1956 Fats Domino hit), MOUNT NIRVANA (42A. Highest peak in the Northwest) and BARBARA EDEN (54A. “I Dream of Jeannie” star) are the interrelated group of this perfectly pleasant Tuesday crossword. Other — BURL IVES (9D. “A Holly Jolly Christmas”