A332991 a(n) is the smallest prime power p^k (p prime, k >= 1) such that sum of reciprocals of prime powers up to p^k (prime power harmonic sum) exceeds n.
2, 4, 19, 1307, 266655247
Offset: 0
Examples
a(1) = 4 because 1/2 + 1/3 = 0.8333... < 1 but 1/2 + 1/3 + 1/4 = 1.0833... > 1.
Links
- Eric Weisstein's World of Mathematics, Prime Power
Crossrefs
Extensions
a(4) from Daniel Suteu, Mar 05 2020
Comments