190815domain: NAppears in sequencesNumber of solutions to the equation p_i = (1+mod(i,2))*p_{i-1} +- p_{i-2} +- p_{i-3} +- ... +- 2 +- 1, where p_i is the i-th prime number (where p_1 = 2 and the "zeroth prime" p_0 is defined to be 1).at n=26A059871Numbers k such that 2*k+1, 4*k+1, 8*k+1, 16*k+1 and 32*k+1 are primes.at n=23A124413