Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k 3-term arithmetic progressions (n>=0; 0<=k<=floor((n-1)^2/4)).

A162982

Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k 3-term arithmetic progressions (n>=0; 0<=k<=floor((n-1)^2/4)).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =2a(5) =10a(6) =12a(7) =2a(8) =20a(9) =48a(10) =46a(11) =4a(12) =2a(13) =48a(14) =156a(15) =318a(16) =152a(17) =40a(18) =4a(19) =2a(20) =104a(21) =460a(22) =1112a(23) =1690a(24) =1152a(25) =406a(26) =92a(27) =18a(28) =4a(29) =2

External references