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 A164276 #19 Mar 01 2022 07:25:35 %S A164276 0,1,8,9,10,14,15,16,20,21,22,24,25,26,27,28,32,33,34,35,36,38,39,40, %T A164276 44,45,46,48,49,50,51,52,54,55,56,57,58,62,63,64,65,66,68,69,70,74,75, %U A164276 76,77,78,80,81,82,84,85,86,87,88,90,91,92,93,94,95,96,98,99,100,104,105,106,110 %N A164276 The non-isolated nonprimes. %C A164276 Non-isolated nonprimes in the sense that at least one of the two adjacent integers is also a nonprime. %H A164276 G. C. Greubel, <a href="/A164276/b164276.txt">Table of n, a(n) for n = 1..1000</a> %F A164276 A141468 \ A014574. %F A164276 a(n) = n + n / log n + O(n / (log n)^2) by Brun's theorem. - _Charles R Greathouse IV_, Mar 15 2011 %t A164276 Select[Range[0,100], !PrimeQ[#] && (!PrimeQ[# - 1] || !PrimeQ[# + 1]) & ] (* _G. C. Greubel_, Jul 07 2016 *) %o A164276 (PARI) isA164276(n) = !isprime(n)&&(!isprime(n-1)||!isprime(n+1)) \\ _Michael B. Porter_, Feb 02 2010 %Y A164276 Cf. A014574, A141468. %K A164276 nonn,easy %O A164276 1,3 %A A164276 _Juri-Stepan Gerasimov_, Aug 11 2009 %E A164276 40 added by _R. J. Mathar_, Aug 27 2009