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 A008471 #29 Jul 27 2025 18:46:36
%S A008471 4,7,13,22,31,43,46,61,64,85,88,103,106,109,130,142,145,160,166,169,
%T A008471 178,199,238,268,271,316,367,376,391,400,409,415,421,451,472,478,493,
%U A008471 523,541,544,547,550,574
%N A008471 Exactly 3 out of 10m+1, 10m+3, 10m+7, 10m+9 are primes.
%H A008471 V. Raman, <a href="/A008471/b008471.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Harvey P. Dale)
%t A008471 m3Q[m_]:=Module[{c=10m},Count[{c+1,c+3,c+7,c+9},_?PrimeQ]==3]; Select[ Range[ 600],m3Q] (* _Harvey P. Dale_, Dec 24 2011 *)
%t A008471 Select[Range[600],Total[Boole[PrimeQ[10 #+{1,3,7,9}]]]==3&] (* _Harvey P. Dale_, Jul 27 2025 *)
%o A008471 (Magma) [n: n in [1..600] | #PrimesInInterval(10*n+1, 10*n+9) eq 3]; // _Bruno Berselli_, Sep 04 2012
%Y A008471 Cf. A007811, A032352, A216292, A216293.
%K A008471 nonn
%O A008471 1,1
%A A008471 _Olivier Gérard_