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 A134928 #13 Sep 07 2023 16:09:15 %S A134928 4,6,8,10,12,14,16,18,20,28,30,32,40,42,44,58,60,62,70,72,74,100,102, %T A134928 104,106,108,110,136,138,140,148,150,152,178,180,182,190,192,194,196, %U A134928 198,200,226,228,230,238,240,242,268,270,272,280,282,284 %N A134928 Triple composites. %C A134928 Numbers that are composites and nearest-neighbors of twin primes. %H A134928 Harvey P. Dale, <a href="/A134928/b134928.txt">Table of n, a(n) for n = 1..1000</a> %H A134928 Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y compuesto</a>. %e A134928 28, 30 and 32 are triple composites because 29 and 31 are twin primes and 28, 30 and 32 are composites and nearest-neighbors of 29 and 31. %t A134928 #[[1]]+{-1,1,3}&/@Select[Partition[Prime[Range[3,100]],2,1],#[[2]]-#[[1]]==2&]//Flatten (* _Harvey P. Dale_, Jun 09 2023 *) %t A134928 Flatten[{#[[1]],#[[1]]+2,#[[2]]}&/@SequencePosition[Table[Which[CompositeQ[ n],1,PrimeQ[ n],2,True,0],{n,300}],{1,2,1,2,1}]] (* _Harvey P. Dale_, Sep 07 2023 *) %Y A134928 Cf. Twin primes = A001097, Composite numbers = A002808. %K A134928 easy,nonn %O A134928 1,1 %A A134928 _Omar E. Pol_, Nov 16 2007