Number of ways to arrange integers 1...n so that the sum of each adjacent pair is a triangular number, not counting reversals.

A116980

Number of ways to arrange integers 1...n so that the sum of each adjacent pair is a triangular number, not counting reversals.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =0a(9) =1a(10) =1a(11) =4a(12) =19a(13) =23a(14) =16a(15) =43a(16) =59a(17) =66a(18) =127a(19) =492a(20) =886a(21) =964a(22) =2595a(23) =11426a(24) =36780a(25) =78070a(26) =131232a(27) =423402a(28) =1302893a(29) =3356226

External references