Number of derangements of {1,2,...,n} having no adjacent 4-cycles (an adjacent 4-cycle is a cycle of the form (i,i+1,i+2,i+3)).

A177260

Number of derangements of {1,2,...,n} having no adjacent 4-cycles (an adjacent 4-cycle is a cycle of the form (i,i+1,i+2,i+3)).

Terms

    a(0) =1a(1) =0a(2) =1a(3) =2a(4) =8a(5) =44a(6) =262a(7) =1846a(8) =14789a(9) =133232a(10) =1333112a(11) =14669758a(12) =176081478a(13) =2289458896a(14) =32056423888a(15) =480890367598

External references