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 A361208 #29 Oct 17 2023 07:39:27 %S A361208 1,1,1,2,1,2,1,1,2,2,2,2,1,1,2,2,2,2,2,2,1,2,3,2,2,2,2,2,1,2,2,2,4,2, %T A361208 1,2,2,3,2,2,2,1,2,2,4,2,1,2,1,2,2,2,2,2,2,2,2,4,4,1,2,2,2,2,2,2,3,2, %U A361208 2,2,2,2,2,2,1,2,4,2,2,2,4,2,2,4,2,2,2,1,2,3,2,2,2,4,4,2,2,3,2,2,2,2,2,2,4 %N A361208 Number of middle divisors of the n-th number whose divisors increase by a factor of 2 or less. %C A361208 The middle divisors of n are the divisors in the half-open interval [sqrt(n/2), sqrt(n*2)). %C A361208 Also consider the n-th number k with the property that the symmetric representation of sigma(k) has only one part. a(n) is the number of square cells on the axis of symmetry of the diagram. %C A361208 For the diagrams related to the first 13 terms of this sequence see A317305. %F A361208 a(n) = A067742(A174973(n)). %t A361208 With[{$MaxExtraPrecision = 1000}, Map[Function[n, Count[Divisors[n], _?(Sqrt[n/2] <= # < Sqrt[2 n] &)]], Select[Range[500], And @@ Map[# <= 2 &, (Rest[#]/Most[#])] &@ Divisors[#] &]] ] (* _Michael De Vlieger_, Mar 28 2023, after _Harvey P. Dale_ at A174973 *) %Y A361208 Cf. A067742, A174973, A237048, A237270, A237593, A281007, A317305, A354452. %K A361208 nonn %O A361208 1,4 %A A361208 _Omar E. Pol_, Mar 06 2023