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 A320340 #10 Feb 16 2025 08:33:56
%S A320340 1,2,3,4,5,7,8,9,10,11,13,14,15,16,17,19,20,22,23,25,26,27,28,29,31,
%T A320340 32,33,34,35,37,38,39,40,41,43,44,45,46,47,49,50,51,52,53,55,56,57,58,
%U A320340 59,61,62,64,67,68,69,70,71,73,74,75,76,77,79,80,81,82,83
%N A320340 Heinz numbers of double-free integer partitions.
%C A320340 The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).
%C A320340 An integer partition is double-free if no part is twice any other part.
%C A320340 Also numbers n such that if prime(m) divides n then prime(2m) does not divide n, i.e., numbers not divisible by any element of A319613.
%H A320340 Alois P. Heinz, <a href="/A320340/b320340.txt">Table of n, a(n) for n = 1..20000</a>
%H A320340 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Double-FreeSet.html">Double-Free Set</a>
%e A320340 The sequence of all integer partitions whose Heinz numbers belong to the sequence begins: (), (1), (2), (11), (3), (4), (111), (22), (31), (5), (6), (41), (32), (1111), (7), (8), (311), (51), (9), (33), (61), (222), (411).
%t A320340 primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
%t A320340 Select[Range[100],Intersection[primeMS[#],2*primeMS[#]]=={}&]
%Y A320340 Cf. A018819, A056239, A087897, A101417, A112798, A120641, A276431, A305148, A319613, A323092, A323093.
%K A320340 nonn
%O A320340 1,2
%A A320340 _Gus Wiseman_, Jan 07 2019