[Davis 11.4] 11.7.8 (Series solution of 2nd order DE at ordinary point.) First 4 non-zero terms. 11.4.8 (Ditto.) First 4 non-zero terms. [Davis 11.5] 2. (Locate and classify singular point(s).) 6. (Find and solve indicial equation.) 18. Obtain only the first 2 (not 4) non-zero terms for each root of the indicial equation.