A119603 - OEIS

%I #4 Nov 05 2023 09:02:12

%S 22,23,222,33,25,223,27,35,2222,233,225,37,211,2223,55,213,333,227,

%T 235,22222,311,217,57,2233,219,313,2225,237,2211,335,223,22223,77,255,

%U 317,2213,2333,511,2227,319,229,2235,231,337,222222,513,2311,2217,323,257

%N Merging prime factors of n-th composite number.

%C Rule "replace n-th composite number by concatenation of its prime factors" in A037271; composite numbers A002808.

%e 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 Sow[FromDigits@Flatten[Table[IntegerDigits[ #[[1]]],{#[[2]]}]&/@FactorInteger@(n)]]],{n,2,115}]][[2,1]]

%Y Cf. A002808, A037271.

%K nonn,base

%O 1,1

%A _Zak Seidov_, Jun 03 2006