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 A176039 #5 Oct 13 2023 06:48:21 %S A176039 1,2,6,9,15,20,25,28,35,42,45,49,63,66,77,88,91,99,104,110,117,121, %T A176039 130,143,153,156,165,169,170,187,190,195,204,209,221,228,231,238,247, %U A176039 255,266,272,273,276,285,289,299,304,322,323,325,342,345,350,357,361,368 %N A176039 Primitive elements of A071562. %C A176039 Members of A071562 which cannot be expressed as the product of two smaller elements of that sequence. %C A176039 This definition is made to include 1; it would make about as much sense to exclude it. %C A176039 This sequence includes all numbers of the form a*p, where p/2 < a <= p, for p prime. It also includes all p*q*r, where p, q, and r are odd primes, and p*q/2 < r < p*q. Similar but increasingly complex conditions can be made for products of more primes. %e A176039 4 is not in the sequence, because 4 = 2*2, and 2 is in A071562. %K A176039 nonn %O A176039 1,2 %A A176039 _Franklin T. Adams-Watters_, Apr 07 2010