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 A228135 #10 Nov 19 2021 11:46:17 %S A228135 278,1945,2545,4045,5389,9134,9289,12634,17678,23578,25034,25178, %T A228135 27289,32245,32689,34889,35078,40234,42289,47578,47789,48979,50579, %U A228135 51434,51589,55534,55634,55934,57289,57779,69334,69478,70178,70234,71945,71989,72134,76345 %N A228135 Smaller of two consecutive semiprimes which are anagrams of each other. %C A228135 Given the n-th semiprime, it is occasionally possible to form the (n+1)-th semiprime using the same digits in a different order. %C A228135 "Anagram" means that both semiprimes must not only use the same digits but must use each digit the same number of times. %e A228135 278 and 287 are two successive semiprimes. %p A228135 with(numtheory):T:=array(1..50000):k:=0:for i from 1 to 200000 do:if bigomega(i)=2 then k:=k+1:T[k]:=i:else fi:od:for n from 1 to k-1 do:p1:=T[n]:p2:= T[n+1]:pp1:=convert(p1,base,10): pp2:=convert(p2,base,10):n1:=sort(pp1):n2:=sort(pp2): if n1=n2 then printf(`%d, `,p1):else fi:od: %t A228135 range[n_Integer]:=Select[Range@n,PrimeOmega@#==2&]; %t A228135 anagramQ[l_List]:=(l1=Sort@#&/@IntegerDigits@l;l1[[1]]==l1[[2]]); %t A228135 Select[Partition[range@100000,2,1],anagramQ]\[Transpose]//First (* _Hans Rudolf Widmer_, Oct 06 2021 *) %Y A228135 Cf. A001358, A069567. %K A228135 nonn,base,less %O A228135 1,1 %A A228135 _Michel Lagneau_, Aug 12 2013