Is it obligatory for one who had anal intercourse with his wife and forgot the number of times to fast for 60 days only, or must he do something else for repentance?

Having anal intercourse with one's wife is forbidden and carries no expiation. Rather, repentance to Allah the Almighty is obligatory. The husband must sincerely repent, no matter how often he committed this act, for sincere repentance erases previous sins, and one who repents from a sin is like one who has no sin. A general repentance, in which he intends to abandon all sins, is sufficient for him if he does not remember his specific transgressions.