Number of odd permutations on {1,2,...,n} with exactly 2 weak excedances.

Terms

a(0) =0a(1) =0a(2) =0a(3) =3a(4) =4a(5) =15a(6) =26a(7) =63a(8) =120a(9) =255a(10) =502a(11) =1023a(12) =2036a(13) =4095a(14) =8178a(15) =16383a(16) =32752a(17) =65535a(18) =131054a(19) =262143a(20) =524268a(21) =1048575a(22) =2097130a(23) =4194303a(24) =8388584a(25) =16777215a(26) =33554406a(27) =67108863a(28) =134217700a(29) =268435455