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 A340597 #9 Jan 19 2021 09:44:54 %S A340597 4,12,18,27,32,48,64,72,80,96,108,120,128,144,160,180,192,200,240,256, %T A340597 270,288,300,320,360,384,400,405,432,448,450,480,500,540,576,600,640, %U A340597 648,672,675,720,750,768,800,864,896,900,960,972,1000,1008,1024,1080 %N A340597 Numbers with an alt-balanced factorization. %C A340597 We define a factorization into factors > 1 to be alt-balanced if its length is equal to its greatest factor. %e A340597 The sequence of terms together with their prime signatures begins: %e A340597 4: (2) 180: (2,2,1) 450: (1,2,2) %e A340597 12: (2,1) 192: (6,1) 480: (5,1,1) %e A340597 18: (1,2) 200: (3,2) 500: (2,3) %e A340597 27: (3) 240: (4,1,1) 540: (2,3,1) %e A340597 32: (5) 256: (8) 576: (6,2) %e A340597 48: (4,1) 270: (1,3,1) 600: (3,1,2) %e A340597 64: (6) 288: (5,2) 640: (7,1) %e A340597 72: (3,2) 300: (2,1,2) 648: (3,4) %e A340597 80: (4,1) 320: (6,1) 672: (5,1,1) %e A340597 96: (5,1) 360: (3,2,1) 675: (3,2) %e A340597 108: (2,3) 384: (7,1) 720: (4,2,1) %e A340597 120: (3,1,1) 400: (4,2) 750: (1,1,3) %e A340597 128: (7) 405: (4,1) 768: (8,1) %e A340597 144: (4,2) 432: (4,3) 800: (5,2) %e A340597 160: (5,1) 448: (6,1) 864: (5,3) %e A340597 For example, there are two alt-balanced factorizations of 480, namely (2*3*4*4*5) and (2*2*2*2*5*6), so 480 in the sequence. %t A340597 facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]]; %t A340597 Select[Range[100],Select[facs[#],Length[#]==Max[#]&]!={}&] %Y A340597 Numbers with a balanced factorization are A100959. %Y A340597 These factorizations are counted by A340599. %Y A340597 The twice-balanced version is A340657. %Y A340597 A001055 counts factorizations. %Y A340597 A045778 counts strict factorizations. %Y A340597 A316439 counts factorizations by product and length. %Y A340597 Other balance-related sequences: %Y A340597 - A010054 counts balanced strict partitions. %Y A340597 - A047993 counts balanced partitions. %Y A340597 - A098124 counts balanced compositions. %Y A340597 - A106529 lists Heinz numbers of balanced partitions. %Y A340597 - A340596 counts co-balanced factorizations. %Y A340597 - A340598 counts balanced set partitions. %Y A340597 - A340600 counts unlabeled balanced multiset partitions. %Y A340597 - A340653 counts balanced factorizations. %Y A340597 - A340654 counts cross-balanced factorizations. %Y A340597 - A340655 counts twice-balanced factorizations. %Y A340597 Cf. A006141, A064174, A117409, A200750, A303975, A324518, A324522, A325134, A340607, A340608, A340611, A340656. %K A340597 nonn %O A340597 1,1 %A A340597 _Gus Wiseman_, Jan 15 2021