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 A381856 #18 Mar 29 2025 15:44:30 %S A381856 1,1,2,1,2,2,3,1,3,2,4,3,3,4,4,1,5,2,5,3,4,5,4,6,1,5,6,6,2,3,7,5,6,4, %T A381856 6,1,7,7,8,5,7,8,8,9,6,9,2,8,3,7,4,5,9,9,8,10,9,10,10,11,7,1,8,10,11, %U A381856 11,6,11,9,12,10,2,12,8,11,13,12,12,3,10,13,13 %N A381856 Lexicographically earliest sequence of positive integers such that for any value k, no two sets of two or more indices at which k occurs have the same standard deviation. %C A381856 A382381 gives the indices of 1s in this sequence. %C A381856 If the definition is modified to compare all sets of indices whose terms are equal (not just those sets with the same value k), we get A337226. %H A381856 Pontus von Brömssen, <a href="/A381856/b381856.txt">Table of n, a(n) for n = 1..10000</a> %e A381856 a(13) = 3: a(13) cannot be 1 as i = 4,13 would have the same standard deviation as i = 1,4,8,13 (namely 4.5). We cannot have a(13) = 2 because i = 3,6 would have the same standard deviation as i = 10,13 (namely 1.5). With a(13) = 3, we find that no two subsets of i = 7,9,12,13 have the same standard deviation, so a(13) = 3. %Y A381856 Cf. A382381, A337226, A380968, A380783, A380751. %K A381856 nonn %O A381856 1,3 %A A381856 _Neal Gersh Tolunsky_, Mar 08 2025