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 A121660 #25 Sep 15 2024 10:55:21
%S A121660 4,25,229,2315,32639,491900,10362539,228467758,5722056489,
%T A121660 149001936472,4922785960065,167523724578682,5868253146213935,
%U A121660 223161143280708212,8709152841093834203,400844191833597081550,19650074552687350830153
%N A121660 Duplicate of A118835.
%C A121660 Previous name was: Numerator of fraction equal to the continued fraction [4, 6, 9, ..., semiprime(n)].
%C A121660 Apparently the same as A118835. - _Georg Fischer_, Oct 03 2018
%H A121660 Robert Israel, <a href="/A121660/b121660.txt">Table of n, a(n) for n = 1..376</a>
%F A121660 Numerator of fraction equal to the continued fraction [4, 6, 9, ..., A001358(n)].
%e A121660 a(1) = numerator of 4 = 4.
%e A121660 a(2) = numerator of 4 + 1/6 = numerator of 25/6 = 25.
%e A121660 a(3) = numerator of 4 + 1/(6+1/9) = numerator of 229/55 = 229.
%e A121660 a(10) = numerator of 4+1/(6+1/(9+1/(10+ 1/(14+1/(15+ 1/(21+1/(22+1/(25+1/(26))))))))) = numerator of 149001936472/35786212191 = 149001936472.
%p A121660 SP:= select(t -> numtheory:-bigomega(t)=2, [$4..100]):
%p A121660 seq(numer(numtheory:-cfrac(SP[1..n])),n=1..nops(SP)); # _Robert Israel_, Jul 10 2018
%t A121660 Module[{nn=70,sps},sps=Select[Range[nn],PrimeOmega[#]==2&];Table[Numerator[ FromContinuedFraction[ Take[sps,n]]],{n,Length[sps]}]] (* _Harvey P. Dale_, Jan 09 2024 *)
%K A121660 dead
%O A121660 1,1
%A A121660 _Jonathan Vos Post_, Aug 14 2006
%E A121660 More terms from _Arkadiusz Wesolowski_, Jul 03 2011