You are given a paragraph, with numbered sentences, and a question. Write the numbers of the sentences needed to answer the given question. Separate multiple sentence numbers with a comma (", "). E.g. "1, 2" would be the correct response if Sent 1 and Sent 2 are needed to answer the given question (do not include sentences that contain no information that is necessary to answer the question). Sort the sentence numbers in an increasing order (i.e., '1, 2', instead of '2, 1'). Your answer should not contain anything than the sentence numbers separated by a comma (e.g. '1, 2, 3, 4'). The given question requires more than one sentence to answer. So, your answer must contain at least one comma (", ").
Q: Paragraph- Sent 1: Born in Moscow, Pushkin published his first poem at the age of fifteen.
Sent 2: By the time he finished school as part of the first graduating class of the prestigious Imperial Lyceum in Tsarskoe Selo near Saint Petersburg, his talent was already widely recognized within the Russian literary scene.
Sent 3: After school, Pushkin plunged into the vibrant and raucous intellectual youth culture of the capital, Saint Petersburg.
Sent 4: In 1820 he published his first long poem, Ruslan and Lyudmila, amidst much controversy about its subject and style.
Sent 5: Pushkin gradually became committed to social reform and emerged as a spokesman for literary radicals.
Sent 6: This angered the government, and led to his transfer from the capital (1820).
Sent 7: He went to the Caucasus and to the Crimea, then to Kamenka and Chisinau, where he became a Freemason. 
Question: What was going on with Pushkin in 1820?.
A: 
4, 6.