This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A176212 #12 Jan 06 2021 12:45:11
%S A176212 6,9,13,20,31,36,49,54,78,81,117,120,125,169,180,186,201,216,260,279,
%T A176212 294,324,400,403,441,468,486,523,620,637,702,720,729,750,845,961,980,
%U A176212 1014,1053,1080,1116,1125,1206,1296,1366,1519,1521,1560,1620,1625,1674,1764,1809,1944,2197
%N A176212 Terms of A176211, duplicates removed.
%C A176212 The terms are permanents of a set of certain symmetric (0,1)-matrices as detailed in A176211. Thus the sequence solves a symmetric version of Gristein problem: to find all the values of permanent of all square (0,1) matrices, which contain exactly three 1's in each row and column (see the list of unsolved problems in chapter 8 of Minc's book).
%D A176212 H. Minc, Permanents, Addison-Wesley, 1978.
%H A176212 V. S. Shevelev, <a href="http://dx.doi.org/10.1007/BF01104103">Some problems of the theory of enumerating the permutations with restricted position</a>, Journal of Soviet Mathematics, 61 (4) (1992) 2272-2317
%o A176212 (PARI) f(n) = fibonacci(n+1) + fibonacci(n-1) + 2; \\ A000211
%o A176212 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,,8));}
%o A176212 lista(14) \\ _Michel Marcus_, Jan 06 2021
%Y A176212 Cf. A176211, A176210, A000211.
%K A176212 nonn
%O A176212 1,1
%A A176212 _Vladimir Shevelev_, Apr 12 2010