Number of essentially different permutations of the numbers 1 to n such that the sum of adjacent numbers is a square.

A090460

Number of essentially different permutations of the numbers 1 to n such that the sum of adjacent numbers is a square.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =3a(9) =0a(10) =10a(11) =12a(12) =35a(13) =52a(14) =19a(15) =20a(16) =349a(17) =361a(18) =637a(19) =3678a(20) =15237a(21) =11875a(22) =13306a(23) =10964a(24) =27223a(25) =37054a(26) =201408a(27) =510152a(28) =1995949a(29) =4867214

External references