203069domain: NAppears in sequencesa(n) = numerator of Sum_{i=1..n} +-1/n, where the sign is -1 iff n is prime.at n=13A114998Odd numbers m such that for all 2^k < m the numbers m + 2^k, m - 2^k, m*2^k + 1, and m*2^k - 1 are composite, with k >= 1.at n=26A256163