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70 contains an [[aliquot sum]] of [[74 (number)|74]], in an [[aliquot sequence]] of four composite numbers (70, 74, [[40 (number)|40]], [[50 (number)|50]], [[43 (number)|43]]) in the prime [[43 (number)|43]]-aliquot tree.
* The [[Composite number|composite index]] of 70 is 50,<ref name="A002808">{{Cite OEIS |A002808 |The composite numbers. |access-date=2024-07-31 }}</ref> which is the first non-trivial member of the 43-aliquot tree.
* 40, the [[Euler totient]] of [[100]] (as twice 50), is the second non-trivial member of the 43-aliquot tree.
* The composite index of 100 is 74 (the aliquot part of 70),<ref name="A002808" /> the third non-trivial member of the 43-aliquot tree.
The sum 43 + 50 + 40 = [[133 (number)|133]] represents the one-hundredth composite number,<ref name="A002808" /> where the sum of all members in this aliquot sequence up to 70 is the forty-ninth prime, [[277 (number)|277]].<ref>{{Cite OEIS |A000040 |The prime numbers. |access-date=2024-07-31 }}</ref>
==== Central binomial coefficient ====
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