153720
domain: N
Appears in sequences
- Numbers k such that phi(k) + sigma(k) = 4*k.at n=2A011254
- Nonprimes k that divide sigma(k) + phi(k).at n=9A011774
- Numbers m that raised to the powers from 1 to k (with k>=1) are multiple of the sum of their digits (m raised to k+1 must not be a multiple). Case k=15.at n=7A135200
- a(n) = 196*n^2 + 2*n.at n=27A158222
- Exponential Riordan array [1+x^2*sec(x), x].at n=57A166378
- Expansion of e.g.f. 1/(1 + (log(1 - x^2))/x)^2.at n=7A375806
- Least positive integer that gives a square of an integer when multiplied by the n-th harmonic number.at n=9A382329