11757173domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumerator of Sum_{k=0..n} (-1)^k/(2*k+1).at n=10A007509a(n) = numerator( (1/(4*n + 2))*Sum_{i=0..2*n} (-1)^i/(2*i+1) ).at n=5A392685Prime numbersat n=773140