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 A137462 #9 Oct 03 2015 22:57:53
%S A137462 1,3,3,6,4,10,5,16,6,19,7,26,8,27,11,28,18,31,20,35,22,36,26,39,30,44,
%T A137462 33,49,36,50,37,54,39,55,40,66,45,70,48,71,50,72,51,78,55,79,62,80,63,
%U A137462 82,64,91,67,92,69,97,72,105,73,110,75,112,82,119,83,120,85,121,88,125
%N A137462 a(n) + a(n-1) = n-th semiprime.
%C A137462 This is to A001358 as A036467 is to A000040.
%H A137462 Harvey P. Dale, <a href="/A137462/b137462.txt">Table of n, a(n) for n = 0..1000</a>
%F A137462 a(n) + a(n-1) = A001358(n).
%p A137462 A001358 := proc(n) option remember ; if n =1 then 4; else for a from A001358(n-1)+1 do if numtheory[bigomega](a) = 2 then RETURN(a) ; fi ; od: fi ; end: A137462 := proc(n) option remember; if n =0 then 1; else A001358(n)-A137462(n-1) ; fi ; end: seq(A137462(n),n=0..100) ; # _R. J. Mathar_, Apr 23 2008
%t A137462 Module[{nn=300,sp,k=1},sp=Select[Range[nn],PrimeOmega[#]==2&];Join[{1}, Table[k=sp[[n]]-k,{n,Length[sp]}]]] (* _Harvey P. Dale_, Apr 30 2015 *)
%Y A137462 Cf. A001358, A036467, A065516.
%K A137462 easy,nonn
%O A137462 0,2
%A A137462 _Jonathan Vos Post_, Apr 19 2008
%E A137462 More terms from _R. J. Mathar_, Apr 23 2008