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 A032620 #17 May 13 2025 11:33:57 %S A032620 12,16,18,28,46,64,76,78,82,88,102,126,132,138,148,154,178,184,186, %T A032620 196,208,214,226,228,234,246,264,282,288,298,316,318,322,324,328,342, %U A032620 348,352,372,408,418,424,432,438,442,444,456,462,468,472,474,478,484 %N A032620 Numbers k such that k concatenated with k+5 is a prime. %H A032620 Robert Israel, <a href="/A032620/b032620.txt">Table of n, a(n) for n = 1..10000</a> %p A032620 filter:= n -> isprime(n * 10^(1+ilog10(n+5)) + n + 5): %p A032620 select(filter, [seq(i,i=2..1000,2)]); # _Robert Israel_, May 13 2025 %t A032620 nc5pQ[n_]:=PrimeQ[FromDigits[Join[IntegerDigits[n],IntegerDigits[n+5]]]]; Select[Range[500],nc5pQ] (* _Harvey P. Dale_, Mar 25 2016 *) %Y A032620 Cf. A032610. %K A032620 nonn,base %O A032620 1,1 %A A032620 _Patrick De Geest_, May 15 1998