OFFSET
1,1
COMMENTS
Values represented by more than one set of indices are listed once per set; otherwise A176212 results.
Each term is a permanent of a quadratic symmetric (0,1) matrix with 1's on the main diagonal and exactly three 1's in each row and column.
LINKS
V. S. Shevelev, Some problems of the theory of enumerating the permutations with restricted position, Journal of Soviet Mathematics, 61 (4) (1992) 2272-2317.
PROG
(PARI) f(n) = fibonacci(n+1) + fibonacci(n-1) + 2; \\ A000211
lista(nn) = {my(v = vector(nn, k, f(k+2))); my(vmax = vecmax(v)); my(w = vector(nn, k, [0, logint(vmax, v[k])])); my(list=List()); forvec(x = w, if (vecmax(x), my(y = prod(k=1, #v, v[k]^x[k])); if (y <= vmax, listput(list, y)); ); ); Vec(vecsort(list)); }
lista(14) \\ Michel Marcus, Jan 06 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Apr 12 2010
STATUS
approved