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 A094457 #16 Oct 11 2023 11:26:38
%S A094457 1,2,2,3,4,5,4,6,6,7,8,11,10,10,8,13,12,17,12,15,14,19,16,15,22,18,20,
%T A094457 23,20,29,16,22,26,25,24,31,34,33,24,37,30,41,28,30,38,43,32,35,30,39,
%U A094457 44,47,36,35,40,51,46,53,40,59,58,45,32,55,44,61,52,57,50,67,48,71,62
%N A094457 a(n) is the largest number k < n in a neighborhood of n defined by prime factorization, specifically, A127185(n,k) <= 2.
%C A094457 Old name: Greatest number strictly less than n with same factorization pattern.
%C A094457 Here we call a number "comparable" if it is in the specified neighborhood of n. For n > 1, A064802(n) is the next larger comparable number. If n is not a power of 2, the ratio of a(n) to n is the ratio of successive primes.
%H A094457 Michael De Vlieger, <a href="/A094457/b094457.txt">Table of n, a(n) for n = 2..10000</a>
%e A094457 a(18)=12 because 18=2*3*3 and next smaller comparable factorization is 2*2*3=12 (A127185(18,12) = 2).
%t A094457 f[n_] := Block[{g, h}, g[x_] := Flatten[Table[#1, {#2}] & @@@ FactorInteger@ x]; h[x_] := If[x == 2, 1, NextPrime[x, -1]]; If[n == 1, 1, Max[Times @@ MapAt[h, g[n], #] & /@ Range[Length@ g[n]]]]]; Table[f@ i, {i, 2, 74}] (* _Michael De Vlieger_, Jan 31 2015 *)
%Y A094457 Cf. A064802, A094456, A094521, A127185.
%K A094457 easy,nonn
%O A094457 2,2
%A A094457 _Marc LeBrun_, May 06 2004
%E A094457 Edited, with new name, by _Peter Munn_, Oct 10 2023