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 A088724 #12 Jul 09 2022 12:17:46 %S A088724 6,18,20,40,54,56,66,78,80,100,102,110,112,114,138,140,160,162,174, %T A088724 182,186,198,200,222,224,234,246,258,260,272,282,318,320,340,354,364, %U A088724 366,392,400,402,414,426,438,448,460,474,486,498,500,506,520,522,534,544 %N A088724 Numbers having exactly one divisor d>1 such that also d+1 is a divisor. %C A088724 Subsequence of A088723. %C A088724 The numbers of terms not exceeding 10^k, for k = 1, 2, ..., are 1, 10, 100, 976, 9712, 97140, 971139, 9711054, 97109111, 971091745, ... . Apparently, the asymptotic density of this sequence exists and equals 0.097109... . - _Amiram Eldar_, Jul 09 2022 %H A088724 Harvey P. Dale, <a href="/A088724/b088724.txt">Table of n, a(n) for n = 1..1000</a> %F A088724 A088722(a(n)) = 1. %t A088724 Select[Range[600],Count[Differences[Rest[Divisors[#]]],1]==1&] (* _Harvey P. Dale_, Sep 05 2015 *) %Y A088724 Cf. A088722, A088723, A088725, A088726. %K A088724 nonn %O A088724 1,1 %A A088724 _Reinhard Zumkeller_, Oct 12 2003 %E A088724 Extended by _Ray Chandler_, May 29 2008