234161domain: NPropertiesPrimalityPrimeyesAppears in sequencesa(n) = Sum_{k=1..n} sigma_{n-k}(k), where sigma_m(k) = Sum_{j|k} j^m.at n=11A108639Least prime p such that the decimal expansion of p^2 contains exactly n distinct primes as substrings.at n=23A385709Prime numbersat n=20758