Number of increasing sequences of n integers x(1),...,x(n) with values in 1..2*n such that x(j) divides x(k) if j divides k.

A180384

Number of increasing sequences of n integers x(1),...,x(n) with values in 1..2*n such that x(j) divides x(k) if j divides k.

Terms

    a(0) =2a(1) =4a(2) =11a(3) =15a(4) =48a(5) =48a(6) =113a(7) =89a(8) =78a(9) =42a(10) =106a(11) =174a(12) =359a(13) =224a(14) =189a(15) =173a(16) =369a(17) =515a(18) =1047a(19) =1562a(20) =1428a(21) =592a(22) =1205a(23) =2067a(24) =2072a(25) =894a(26) =861a(27) =862a(28) =1751a(29) =2613

External references