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 A145199 #25 Sep 08 2022 08:45:38 %S A145199 4,12,16,18,28,36,40,52,60,72,88,96,100,108,112,126,136,148,150,156, %T A145199 162,172,180,192,196,198,228,232,240,250,256,268,270,276,280,292,306, %U A145199 312,316,336,348,352,372,378,388,396,400,408,420,432,448,456,460,486,490 %N A145199 Nonsquarefree numbers k such that k+1 is prime. %H A145199 Robert Israel, <a href="/A145199/b145199.txt">Table of n, a(n) for n = 1..10000</a> %F A145199 a(n) = A049092(n) - 1. - _Amiram Eldar_, Feb 10 2021 %e A145199 4 is in the sequence because it is not squarefree and 5 is prime. - _Emeric Deutsch_, Oct 12 2008 %p A145199 with(numtheory): a:=proc(n) if issqrfree(n)=false and isprime(n+1)=true then n else end if end proc: seq(a(n),n=1..600); # _Emeric Deutsch_, Oct 12 2008 %p A145199 with(numtheory): a:=proc(k) if issqrfree(ithprime(k)-1)=false then ithprime(k)-1 else end if end proc: seq(a(k),k=1..110); # _Emeric Deutsch_, Oct 12 2008 %t A145199 Select[Prime[Range[120]]-1, !SquareFreeQ[ # ]&] (* _T. D. Noe_, Oct 06 2008 *) %o A145199 (Magma) [n: n in [1..5*10^2]| not IsSquarefree(n) and IsPrime(n+1)]; // _Vincenzo Librandi_, Dec 24 2015 %o A145199 (PARI) is(n)=isprime(n+1) && !issquarefree(n) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A145199 Cf. A006093, A013929, A049092, A077064. Includes A152680. %K A145199 easy,nonn %O A145199 1,1 %A A145199 _Giovanni Teofilatto_, Oct 04 2008 %E A145199 Corrected and extended by _T. D. Noe_, _Emeric Deutsch_ and _R. J. Mathar_, Oct 05 2008