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 A119603 #10 Jun 28 2025 09:25:43
%S A119603 22,23,222,33,25,223,27,35,2222,233,225,37,211,2223,55,213,333,227,
%T A119603 235,22222,311,217,57,2233,219,313,2225,237,2211,335,223,22223,77,255,
%U A119603 317,2213,2333,511,2227,319,229,2235,231,337,222222,513,2311,2217,323,257
%N A119603 Merging prime factors of n-th composite number.
%C A119603 Rule "replace n-th composite number by concatenation of its prime factors" in A037271; composite numbers A002808.
%F A119603 a(n) = A037276(A002808(n)). - _Jason Yuen_, Jun 28 2025
%e A119603 a(6)=223 because 6th composite number is 12: A002808(6)=12, then 12=2*2*3 and merging prime factors we get a(6)=223.
%t A119603 Reap[Do[If[!PrimeQ[n],Sow[FromDigits@Flatten[Table[IntegerDigits[ #[[1]]],{#[[2]]}]&/@FactorInteger@(n)]]],{n,2,115}]][[2,1]]
%Y A119603 Cf. A002808, A037271, A037276.
%K A119603 nonn,base
%O A119603 1,1
%A A119603 _Zak Seidov_, Jun 03 2006