Number of nondecreasing arrangements of n numbers x(i) in -n..n with the sum of sign(x(i))*2^|x(i)| zero.

A187981

Number of nondecreasing arrangements of n numbers x(i) in -n..n with the sum of sign(x(i))*2^|x(i)| zero.

Terms

    a(0) =0a(1) =2a(2) =5a(3) =15a(4) =57a(5) =181a(6) =632a(7) =2199a(8) =7593a(9) =26706a(10) =93724a(11) =330555a(12) =1170088a(13) =4149361a(14) =14754670a(15) =52564714a(16) =187595025a(17) =670589799a(18) =2400467901a(19) =8603906865a(20) =30874479617a(21) =110907636467a(22) =398789645747

External references