Number of nondecreasing arrangements of n numbers x(i) in -(n-1)..(n-1) with the sum of sign(x(i))*2^|x(i)| zero.
A187980
Number of nondecreasing arrangements of n numbers x(i) in -(n-1)..(n-1) with the sum of sign(x(i))*2^|x(i)| zero.
Terms
- a(0) =0a(1) =1a(2) =3a(3) =9a(4) =36a(5) =117a(6) =411a(7) =1452a(8) =5040a(9) =17829a(10) =62870a(11) =222458a(12) =789895a(13) =2808018a(14) =10006020a(15) =35713288a(16) =127657287a(17) =456975112a(18) =1637845137a(19) =5876993799a(20) =21110257429a(21) =75900966585a(22) =273140226328a(23) =983733709424
External references
- oeis: A187980