@article{hrj:643, title = {On warning's problem : g (4) < 21}, author = {R Balasubramanian}, url = {https://hrj.episciences.org/643}, doi = {10.46298/hrj.1979.643}, journal = {Hardy-Ramanujan Journal}, issn = {2804-7370}, volume = {Volume 2 - 1979}, eid = 1, year = {1979}, month = {Jan}, keywords = {singular series., Hardy-Littlewood circle method, sum of fourth powers, [MATH]Mathematics [math]}, language = {English}, }