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 A074998 #10 Jan 02 2020 04:15:23 %S A074998 4,6,12,18,30,34,42,51,55,56,60,72,86,92,94,102,108,138,142,144,150, %T A074998 160,180,184,186,192,198,202,204,214,216,218,220,228,236,240,243,248, %U A074998 249,266,270,282,300,302,304,312,320,322,328,340,341,348,392,394,412 %N A074998 Composite numbers which are sandwiched between two numbers having the same unordered canonical form. %C A074998 The average of twin primes is a member. %H A074998 Amiram Eldar, <a href="/A074998/b074998.txt">Table of n, a(n) for n = 1..10000</a> %e A074998 34 is sandwiched between 33 and 35 which are of the form p*q where p and q are primes. %p A074998 k := 0: for j from 2 to 5000 do if not isprime(j) then a := ifactors(j-1): b := ifactors(j+1): if sort([seq(a[2][i][2],i= 1..nops(a[2]))])= sort([seq(b[2][i][2],i= 1..nops(b[2]))]) then k := k+1: c[k] := j: fi: fi: od: seq(c[i],i= 1..k); %Y A074998 Cf. A074997, A061715, A074460. %K A074998 nonn %O A074998 1,1 %A A074998 _Amarnath Murthy_, Aug 21 2002 %E A074998 More terms from _Sascha Kurz_, Aug 22 2002 %E A074998 Offset corrected by _Amiram Eldar_, Jan 02 2020