Revision as of 03:19, 26 February 2022 edit Goudron (talk \| contribs) 271 edits →Other properties and identities: p < q ⇒ p ≠ q, verbal clarification is superfluous; 2^k is not an "example" but a defining predicate with a free variable {{mvar\|k}}; clarify the pairwise use of generalized pentagonal numbers in Euler's recurrence; fix a dead URL to Euler archive; minor copy-ed; canonicalize mark up only unmarked math in text only, the minimum for immediate readability, per WP:MATH. ← Previous edit		Revision as of 01:56, 10 March 2022 edit undo 71.231.185.165 (talk) →Other properties and identities: Fixed typo, only sum natural i Tags: Mobile edit Mobile web edit Next edit →
Line 209: :<math>\begin{align} \sigma(n) &= \sigma(n-1)+\sigma(n-2)-\sigma(n-5)-\sigma(n-7)+\sigma(n-12)+\sigma(n-15)+ \cdots \\[12mu] &= \sum_{i\in\ZN} (-1)^{i+1}\left( \sigma \left( n-\frac{1}{2} \left( 3i^2-i \right) \right) + \sigma \left( n-\frac{1}{2} \left( 3i^2+i \right) \right) \right) \end{align}</math>

Divisor function: Difference between revisions