a(n) is the number of essentially different ways in which the integers 1,2,3,...,n can be arranged in a sequence such that (1) adjacent integers sum to a prime number and (2) squares of adjacent numbers sum to a prime number. Rotations and reversals are counted only once.
A074063
a(n) is the number of essentially different ways in which the integers 1,2,3,...,n can be arranged in a sequence such that (1) adjacent integers sum to a prime number and (2) squares of adjacent numbers sum to a prime number. Rotations and reversals are counted only once.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =0a(5) =1a(6) =0a(7) =0a(8) =0a(9) =3a(10) =1a(11) =1a(12) =0a(13) =0a(14) =0a(15) =0a(16) =0a(17) =0a(18) =0a(19) =0a(20) =0a(21) =0a(22) =0a(23) =0a(24) =0a(25) =0a(26) =0a(27) =0a(28) =0a(29) =0
External references
- oeis: A074063