Number of permutations p from (1,2,3,...,n) to (1,2,3,...,n) such that 1/(1+p(1)) + 1/(2+p(2)) + ... + 1/(n+p(n)) is an integer.
A073112
Number of permutations p from (1,2,3,...,n) to (1,2,3,...,n) such that 1/(1+p(1)) + 1/(2+p(2)) + ... + 1/(n+p(n)) is an integer.
Terms
- a(0) =0a(1) =0a(2) =0a(3) =1a(4) =0a(5) =7a(6) =6a(7) =30a(8) =110a(9) =278a(10) =1332a(11) =3312a(12) =11501a(13) =61165
External references
- oeis: A073112