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 A175218 #14 Oct 06 2024 13:10:17 %S A175218 8,8,9,10,15,16,21,22,26,33,34,40,45,46,50,56,63,64,70,75,76,82,86,92, %T A175218 100,105,106,111,112,116,130,134,141,142,153,154,160,166,170,176,183, %U A175218 184,195,196,201,202,214,226,231,232,236,243,244,254,260,266,273,274 %N A175218 The third nonprimes after the primes. %F A175218 For n>2: a(n) = A000040(n) + 2 + A010051(A000040(n) + 2) + 1. - _Reinhard Zumkeller_, Mar 29 2010 [corrected by _Georg Fischer_, Oct 06 2024] %e A175218 prime(49) = 227, prime(50) = 229, therefore (228=1st, 230=2nd nonprime), 231 = a(49). - _Georg Fischer_, Oct 06 2024 %o A175218 (PARI) a(n) = if(n<=2, 8, prime(n) + 2 + isprime(prime(n)+2) + 1) /* _Georg Fischer_, Oct 06 2024 */ %Y A175218 Cf. A175216, A175217, A175219, A175220. %K A175218 nonn %O A175218 1,1 %A A175218 _Jaroslav Krizek_, Mar 06 2010 %E A175218 More terms from _Reinhard Zumkeller_, Mar 29 2010 %E A175218 a(49), a(52) and a(57) corrected by _Georg Fischer_, Oct 06 2024