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 A131516 #16 Feb 27 2025 10:49:11
%S A131516 0,1,2,1,4,1,6,1,8,9,10,1,12,1,14,15,16,1,18,1,20,21,22,1,24,25,26,27,
%T A131516 28,1,30,1,32,33,34,35,36,1,38,39,40,1,42,1,44,45,46,1,48,49,50,51,52,
%U A131516 1,54,55,56,57,58,1,60,1,62,63,64,65,66,1,68
%N A131516 a(n)=1 if n is an odd prime number, otherwise, a(n)=n.
%t A131516 Table[If[OddQ[n]&&PrimeQ[n],1,n],{n,0,68}] (* _James C. McMahon_, Feb 27 2025 *)
%o A131516 (PARI) a(n) = if ((n%2) && isprime(n), 1, n); \\ _Michel Marcus_, Nov 13 2013
%K A131516 nonn,easy
%O A131516 0,3
%A A131516 _Mohammad K. Azarian_, Aug 14 2007
%E A131516 Offset corrected by _Ivan Panchenko_, Nov 13 2013