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 A214156 #19 Feb 02 2017 12:14:16
%S A214156 0,1,1,2,3,5,8,13,3,16,19,5,24,29,53,2,5,7,12,19,31,50,81,131,212,343,
%T A214156 555,2,557,13,570,11,7,18,5,23,28,3,31,2,3,5,8,13,3,16,19,5,24,29,53,
%U A214156 2,5,7,12,19,31,50,81,131,212,343,555,2,557,13,570,11,7,18
%N A214156 Dual to A214094: a(0)=0, a(1)=1; a(n) = a(n-1) + a(n-2) if a(n-1) + a(n-2) is not semiprime; a(n) is minimal prime divisor of a(n-1) + a(n-2) if a(n-1) + a(n-2) is semiprime.
%C A214156 The sequence has period of length 36: {2,3,5,...,28,3,31} and thus is bounded.
%H A214156 <a href="/index/Rec#order_36">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).
%t A214156 A214156[0]:=0; A214156[1]:=1; A214156[n_] := A214156[n] = If[PrimeOmega[#] == 2, First[Rest[Divisors[#]]], #]& [A214156[n-1] + A214156[n-2]]; Table[A214156[n], {n,0,99}] (* _Peter J. C. Moses_, Feb 18 2013 *)
%t A214156 nxt[{a_,b_}]:={b,If[PrimeOmega[a+b]==2,FactorInteger[a+b][[1,1]],a+b]}; NestList[nxt,{0,1},70][[All,1]] (* or *) PadRight[{0,1,1},70,{28,3,31,2,3,5,8,13,3,16,19,5,24,29,53,2,5,7,12,19,31,50,81,131,212,343,555,2,557,13,570,11,7,18,5,23}] (* _Harvey P. Dale_, Feb 02 2017 *)
%Y A214156 Cf. A214094.
%K A214156 nonn
%O A214156 0,4
%A A214156 _Vladimir Shevelev_, Feb 16 2013