Number of permutations p of (1,2,3,...,n) such that sigma(1+p(1))+sigma(2+p(2))+...+sigma(n+p(n))=2*n^2.

A073110

Number of permutations p of (1,2,3,...,n) such that sigma(1+p(1))+sigma(2+p(2))+...+sigma(n+p(n))=2*n^2.

Terms

    a(0) =0a(1) =1a(2) =0a(3) =2a(4) =10a(5) =37a(6) =121a(7) =725a(8) =5160a(9) =31794a(10) =279136a(11) =2137531a(12) =21305316a(13) =213311303a(14) =2457648287a(15) =30357607661a(16) =387013387043

External references