1259677domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumber of compositions of n with first part 2 and no equal adjacent parts; this is column 2 of the array in A096568.at n=28A096570Primes p such that q=2*p^2-1, r=2*p*q-1 and 2*p*r-1 are also prime.at n=29A224991Prime numbersat n=97163