A card-arranging problem: number of permutations p_1, ..., p_n of 1, ..., n such that i + p_i is a square for every i.

A095986

A card-arranging problem: number of permutations p_1, ..., p_n of 1, ..., n such that i + p_i is a square for every i.

Terms

    a(0) =1a(1) =0a(2) =0a(3) =1a(4) =0a(5) =1a(6) =0a(7) =0a(8) =1a(9) =1a(10) =1a(11) =0a(12) =1a(13) =1a(14) =2a(15) =4a(16) =3a(17) =2a(18) =5a(19) =15a(20) =21a(21) =66a(22) =37a(23) =51a(24) =144a(25) =263a(26) =601a(27) =1333a(28) =2119a(29) =2154

External references