Number of permutations of (1,2,3,...,n) where each of the (n-1) adjacent pairs of elements sums to a prime.

A103839

Number of permutations of (1,2,3,...,n) where each of the (n-1) adjacent pairs of elements sums to a prime.

Terms

    a(0) =1a(1) =2a(2) =2a(3) =8a(4) =4a(5) =16a(6) =24a(7) =60a(8) =140a(9) =1328a(10) =2144a(11) =17536a(12) =23296a(13) =74216a(14) =191544a(15) =2119632a(16) =4094976a(17) =24223424a(18) =45604056a(19) =241559918a(20) =675603568a(21) =8723487720a(22) =22850057800a(23) =285146572432a(24) =859834538938

External references