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 A168270 #7 May 12 2019 02:17:56
%S A168270 2,6,23,30,37,42,47,53,67,79,83,89,97,102,113,127,131,138,157,163,167,
%T A168270 173,211,223,233,251,257,263,277,282,293,307,317,331,337,353,359,367,
%U A168270 373,379,383,389,397,401,409,439,443,449,457,462,467,479,487,491,499,503,509
%N A168270 Squarefree numbers which are also isolated numbers.
%F A168270 A005117 INTERSECT A167706.
%F A168270 A005117 \ A168252.
%p A168270 isA007510 := proc(n) if isprime(n) then not isprime(n-2) and not isprime(n+2) ; else false; end if ; end proc:
%p A168270 isA014574 := proc(n) isprime(n+1) and isprime(n-1) ; end proc:
%p A168270 isA167706 := proc(n) isA007510(n) or isA014574(n) ; end proc:
%p A168270 isA005117 := proc(n) n =1 or numtheory[issqrfree](n) ; end proc:
%p A168270 isA168270 := proc(n) isA005117(n) and isA167706(n) ; end proc:
%p A168270 for n from 1 to 600 do if isA168270(n) then printf("%d,",n) ; fi; od: # _R. J. Mathar_, Dec 09 2009
%Y A168270 Cf. A005117, A167706, A168252.
%K A168270 nonn
%O A168270 1,1
%A A168270 _Juri-Stepan Gerasimov_, Nov 22 2009
%E A168270 Corrected (missing terms inserted) by _R. J. Mathar_, Dec 09 2009