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 A380783 #19 Mar 07 2025 11:06:42 %S A380783 1,2,2,2,2,3,2,3,2,3,2,3,2,3,4,2,2,3,2,4,4,3,2,4,2,3,4,5,2,4,2,5,4,3, %T A380783 5,5,2,3,4,6,2,5,2,5,6,3,2,6,2,3,4,5,2,3,6,4,4,3,2,5,2,3,6,3,6,7,2,5, %U A380783 4,6,2,6,2,3,4,5,7,7,2,7,2,3,2,5,6,3,4 %N A380783 Lexicographically earliest sequence of positive integers such that for any value k, no two sets of one or more indices at which k occurs have the same product. %C A380783 The Fermi-Dirac primes (A050376) are the indices of 2s in this sequence. %H A380783 Dominic McCarty, <a href="/A380783/b380783.txt">Table of n, a(n) for n = 1..10000</a> %H A380783 Dominic McCarty, <a href="/A380783/a380783.txt">Java program for A380783</a> %e A380783 a(8) = 3: We cannot have 1 here because the set of indices i = 8 and i = 1,8 would have the same product. We cannot have a(8) = 2 because i = 8 would have the same product as i = 2,4. So a(8) = 3. %Y A380783 Cf. A050376, A380751, A380921 (indices of records). %K A380783 nonn %O A380783 1,2 %A A380783 _Neal Gersh Tolunsky_, Feb 02 2025