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 A162177 #18 Nov 11 2024 12:27:04
%S A162177 0,0,0,1,2,5,6,9,10,13,18,19,24,27,28,31,36,41,42,47,50,51,56,59,64,
%T A162177 71,74,75,78,79,82,95,98,103,104,113,114,119,124,127,132,137,138,147,
%U A162177 148,151,152,163,174,177,178,181,186,187,196,201,206,211,212,217,220,221
%N A162177 a(n) is the number of composite numbers that are smaller than A008578(n).
%C A162177 Essentially the same as A065890.
%C A162177 a(n) = number of terms of A073169(n) less than n.
%H A162177 Harvey P. Dale, <a href="/A162177/b162177.txt">Table of n, a(n) for n = 1..1000</a>
%F A162177 a(n) = A008578(n) - n = A158611(n+1) -n.
%F A162177 a(n) = A065890(n-1) for n > 1.
%e A162177 A008578(6) = 11, and there are 5 composites smaller than 11, viz. 4, 6, 8, 9, 10, hence a(6) = 5.
%t A162177 Join[{0},Module[{nn=300,cmps},cmps=Accumulate[Table[If[CompositeQ[n],1,0],{n,nn}]];Table[cmps[[p]],{p,Prime[ Range[ PrimePi[ nn]]]}]]] (* _Harvey P. Dale_, Nov 11 2024 *)
%o A162177 (Magma) T:=[0,1] cat PrimesUpTo(300); [ T[n+1]-n: n in [1..#T-1] ]; // _Klaus Brockhaus_, Sep 08 2009
%Y A162177 Cf. A002808 (composites), A008578 (1 and the primes), A065890, A073169.
%K A162177 nonn,easy
%O A162177 1,5
%A A162177 _Jaroslav Krizek_, Jun 27 2009
%E A162177 Edited and extended by _Klaus Brockhaus_, Sep 09 2009