Number of sequences of length n with elements {-2,-1,+1,+2}, such that the sum of elements of the whole sequence but of no proper subsequence equals 0 modulo n. For n>=4, the number of Hamiltonian (directed) circuits on the circulant graph C_n(1,2).
A137725
Number of sequences of length n with elements {-2,-1,+1,+2}, such that the sum of elements of the whole sequence but of no proper subsequence equals 0 modulo n. For n>=4, the number of Hamiltonian (directed) circuits on the circulant graph C_n(1,2).
Terms
- a(0) =4a(1) =4a(2) =16a(3) =18a(4) =24a(5) =32a(6) =46a(7) =58a(8) =82a(9) =112a(10) =158a(11) =220a(12) =316a(13) =450a(14) =650a(15) =938a(16) =1364a(17) =1982a(18) =2892a(19) =4220a(20) =6170a(21) =9022a(22) =13206a(23) =19332a(24) =28314a(25) =41472a(26) =60760a(27) =89022a(28) =130446a(29) =191150
External references
- oeis: A137725